--- loncom/interface/lonstatistics.pm	2002/02/05 12:24:45	1.2
+++ loncom/interface/lonstatistics.pm	2003/02/28 20:50:33	1.61
@@ -1,7 +1,6 @@
 # The LearningOnline Network with CAPA
-# (Publication Handler
 #
-# $Id: lonstatistics.pm,v 1.2 2002/02/05 12:24:45 minaeibi Exp $
+# $Id: lonstatistics.pm,v 1.61 2003/02/28 20:50:33 matthew Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -26,1375 +25,1431 @@
 # http://www.lon-capa.org/
 #
 # (Navigate problems for statistical reports
-# YEAR=2001
-# 5/05/01, 7/09/01, 7/25/01, 8/11/01,9/13/01, 9/26/01 Behrouz Minaei
-# 10/5/01, 10/9/01, 10/22/01, 10/26/01 Behrouz Minaei
-# 11/1/01, 11/4/01, 11/16/01 Behrouz Minaei
-# 12/14/01, 12/16/01, 12/18/01,12/20/01,12/31/01 Behrouz Minaei
-# YEAR=2002
-# 1/22/02,2/1/02
+#
 ###
 
+=pod
+
+=head1 NAME
+
+lonstatistics
+
+=head1 SYNOPSIS
+
+Main handler for statistics and chart.
+
+=head1 PACKAGES USED
+
+    use strict;
+    use Apache::Constants qw(:common :http);
+    use Apache::lonnet();
+    use Apache::lonhomework;
+    use Apache::loncommon;
+    use Apache::loncoursedata;
+    use Apache::lonhtmlcommon;
+    use Apache::lonproblemanalysis;
+    use Apache::lonproblemstatistics;
+    use Apache::lonstudentassessment;
+    use Apache::lonpercentage;
+    use GDBM_File;
+
+=over 4
+
+=cut
+
 package Apache::lonstatistics;
 
 use strict;
 use Apache::Constants qw(:common :http);
+use vars qw(
+    @FullClasslist 
+    @Students
+    @Sections 
+    @SelectedSections
+    %StudentData
+    @StudentDataOrder
+    @SelectedStudentData
+    $top_map 
+    @Sequences 
+    @SelectedMaps
+    @Assessments);
+
 use Apache::lonnet();
 use Apache::lonhomework;
-use HTML::TokeParser;
+use Apache::loncommon;
+use Apache::loncoursedata;
+use Apache::lonhtmlcommon;
+use Apache::lonproblemanalysis();
+use Apache::lonproblemstatistics();
+use Apache::lonstudentassessment();
+use Apache::lonpercentage;
 use GDBM_File;
-use Benchmark;
 
-# -------------------------------------------------------------- Module Globals
-my %hash;
-my %CachData;
-my %GraphDat;
-my %maps;
-my @mapsort;
-my %section;
-my %StuBox;
-my %DiscFac;
-my $CurMap;
-my $CurSec;
-my $CurStu;
-my @cols;
-my @list;
-my @students;
-my $p_count;
-my $Pos;
-my $r;
-my $OpSel1;
-my $OpSel2;
-my $OpSelDis1;
-my $OpSelDis2;
-my $CurDis=0;
-my $OpSel3;
-my $OpSel4;
-my $GData;
-my $cid;
-my $firstres;
-my $lastres;
-my $DiscFlag=0;
-my $HWN=0;
-
-my %Header = (0,"Problem Title",1,"#Stdnts",2,"Tries",3,"Mod",
-              4,"Mean",5,"#YES",6,"#yes",7,"%Wrng",8,"S.D.",
-              9,"Skew.",10,"DoDiff",11,"Map");
-#             9,"Skew.",10,"DoDiff",11,"Dis.F.",12,"Resourse URL");
-
-my %class = qw(
-);
-
-my @LS;
-my @LF;
-
-sub GetBin {
-    my ($Index1,$Index2,$String,$C)=@_;
-    my @step = 5;
-    my @L=($C eq 'S') ? @LS : @LF;
-    my $Count=$#L+1;
-    $r->print("<br>zone   $C ------ $String ");
-    for(my $n=0;$n<$Count;$n++){  
-	my @t=split(/\:/,$L[$n]);
-        $r->print("<br>$t[$Index1] $t[$Index2]");
-    }
-}
-
-sub GetUniqe {
-    my ($Index,$String,$C)=@_;
-    my @step = 5;
-    my @L=($C eq 'S') ? @LS : @LF;
-    my $Count=$#L+1;
-    my @List=();
-    for(my $n=0;$n<$Count;$n++){  
-	my @t=split(/\:/,$L[$n]);
-	push(@List,$t[$Index]);
-        #$r->print("<br>$t[$Index]");
-    }
-    @List = sort NumSort(@List);
-
-    $r->print("<br>zone   $C ------ $String ");
-    my $nIdx=0;
-    my $nPrb=0;
-    my %Proc;
-    undef %Proc;
-    while ( $nIdx < $Count ) {
-	my $Focus=$List[$nIdx];
-	my $Temp = $Focus;
-	do {
-	    $nIdx++;
-	    $nPrb++;
-	    $Focus=$List[$nIdx];
-	    #$Proc{$name}=$Focus;
-	} while ( $Focus == $Temp && $nIdx < $Count );
-        $r->print("<br>$Temp --> $nPrb");
-	$nPrb=0;
-    }
-    return %Proc;
-}
-
-sub GetUniq {
-    my ($Index,$String)=@_;
-    my @step = 5;
-    my $Count=0;
-    my @List=();
-    my @temp=();
-    foreach (keys(%DiscFac)){  
-	$Count++;
-	my @temp1=split(/\:/,$_);
-        @temp=($temp1[$Index],@temp1);
-	push(@List,join(':',@temp));
-    }
-    @List = sort NumericSort(@List);
-
-    $r->print("<br><br>zone ($Index) ------ $String ----- / $temp[3]");
-    my $nIdx=0;
-    my $nPrb=0;
-    my %Proc;
-    undef %Proc;
-    while ( $nIdx < $Count ) {
-	my ($Focus,$Dummy,$name)=split(/\:/,$List[$nIdx]);
-	my $Temp = $Focus;
-	$Proc{$name}=$Focus;
-	do {
-	    $nIdx++;
-	    $nPrb++;
-	    ($Focus,$Dummy,$name)=split(/\:/,$List[$nIdx]);
-	    $Proc{$name}=$Focus;
-	} while ( $Focus == $Temp && $nIdx < $Count );
-        $r->print("<br>$Temp --> $nPrb");
-	$nPrb=0;
-    }
-    return %Proc;
-}
-
-sub NumericSort {          
-    $a <=> $b;
-}
-
-
-#------- Classification  
-sub Classify {
-    my $Count=0;
-    my @List=();
-#    foreach(keys %class){
-#        $r->print("<br>$_ --> $class{$_}");
-#    }
-	   # $DiscFac{($DisFactor.':'.$sname.':'.$ProbTot.':'.$TotalOpend.':'.
-            #          $TotalTries.':'.$ProbSolved.':'.$time)}=$Dis;
-    @LS=();
-    @LF=();
-    my $cf=0;
-    my $cs=0;
-    foreach (keys(%DiscFac)){  
-	my @l=split(/\:/,$_);	
-	if ($class{$l[1]}){
-	    if( $class{$l[1]} == 4 ) {
-		$cs++;
-		push(@LS,('S:'.$l[6].':'.$l[0].':'.$l[5].':'.$l[4].':'.$l[3].':'.$class{$l[1]}));
-	    }	    
-	    elsif ( $class{$l[1]} < 3 ) {
-		$cf++;
-		push(@LF,('F:'.$l[6].':'.$l[0].':'.$l[5].':'.$l[4].':'.$l[3].':'.$class{$l[1]}));
-	    }
-	}
-    }
-    
-    $r->print("<br>zone successful");
-    for(my $n=0;$n<$cs;$n++){
-	$r->print('<br>'.$LS[$n]);
-    }
-
-    $r->print("<br>zone failed");
-    for(my $n=0;$n<$cf;$n++){
-	$r->print('<br>'.$LF[$n]);
-    }
- 
-#    my %Disc = &GetUniqe(@List,5,"Discrimination Factor");    
-#    my %Opnd = &GetUniq(@List,3,"Total Opened");
-#    my %Trys = &GetUniq(@Lsit4,"Total Tries");
-#    my %Slvd = &GetUniq(5,"Problems Solved");
-
-   # my (@L, $Index,$String)=@_;
-
-    my %Time = &GetUniqe(1,"Time",'S');
-    &GetUniqe(1,"Time",'F');
-    &GetUniqe(2,"Discrimination Factor",'S');    
-    &GetUniqe(2,"Discrimination Factor",'F');
-    &GetUniqe(3,"Solved",'S');
-    &GetUniqe(3,"Solved",'F');
-    &GetUniqe(4,"Tries",'S');
-    &GetUniqe(4,"Tries",'F');    
-
-    &GetBin(1,2, "  Time ... Discriminat",'S');
-    &GetBin(1,2, "  Time ... Discriminat",'F');
-    &GetBin(1,3, "  Time ... Solved",'S');
-    &GetBin(1,3, "  Time ... Solved",'F');
-    &GetBin(1,4, "  Time ... Tries",'S');
-    &GetBin(1,4, "  Time ... Tries",'F');
-    &GetBin(2,3, "  Discriminant ... Solved",'S');
-    &GetBin(2,3, "  Discriminant ... Solved",'F');
-    &GetBin(2,4, "  Discriminant ... Tries",'S');
-    &GetBin(2,4, "  Discriminant ... Tries",'F');
-    &GetBin(3,4, "  Solved ... Tries",'S');
-    &GetBin(3,4, "  solved ... Tries",'F');
-#    foreach (keys(%Disc)) {
-#        $r->print("<br>: $Disc{$_} --> $Slvd{$_}");
- #   } 
- #   $r->print("<br>..........Discriminant ...  Time................");
- ##   foreach (keys(%Disc)) {
- #       $r->print("<br>$Disc{$_} --> $Time{$_}");
-  #  } 
-  #  $r->print("<br>..........Time ...  Solved.......................");
-  #  foreach (keys(%Disc)) {
-  #      $r->print("<br>$Disc{$_} --> $Slvd{$_}");
-  #  }  
-}
-
-#------- Processing upperlist and lowerlist according to each problem
-sub ProcessDisc {
-    my @List = @_;
-    @List = sort (@List);
-    my $Count = $#List+1;
-    my $Prb;
-    my @Dis;
-    my $Slvd=0;
-    my $tmp;
-    my $Sum=0;
-    my $nIdx=0;
-    my $nStud=0;
-    my %Proc;
-    undef %Proc;
-    while ($nIdx<$Count) {
-	($Prb,$tmp)=split(/\=/,$List[$nIdx]);
-	@Dis=split(/\+/,$tmp);
-	my $Temp = $Prb;
-	do {
-	    $nIdx++;
-	    $nStud++;
-	    $Sum += $Dis[$CurDis];
-	    ($Prb,$tmp)=split(/\=/,$List[$nIdx]);
-	    @Dis=split(/\+/,$tmp);
-	} while ( $Prb eq $Temp && $nIdx < $Count );
-#	$Proc{$Temp}=$Sum.':'.$nStud;
-	$Proc{$Temp}=($Sum/$nStud).':'.$nStud;
-#        $r->print("$nIdx) $Temp --> ($nPrb) $Proc{$Temp} <br>");
-	$Sum=0;
-	$nStud=0;
-    }
-    return %Proc;
-}
-
-#------- Creating Discimination factor table  
-sub DiscriminationTable {
-    my $Count=0;
-    foreach (keys(%DiscFac)){ 
-	$Count++;
-    }
-    my $UpCnt = int(0.27*$Count);
-    $r->print("<br><br>".
-              "Current map: <b>\"$CurMap\"</b> &nbsp;&nbsp;&nbsp; ".
-              "Current Section: <b>\"$CurSec\" </b>&nbsp;&nbsp;&nbsp;".
-              "Number of valid students: <b>$Count</b>".
-              "<br>The <b>Upper 27%</b> has <b>$UpCnt</b> records.".
-              "&nbsp;&nbsp;The <b>Lower 27%</b> has <b>$UpCnt</b> records <br>".
-              "The Criterion of sorting the students: ". 
-              "<b>( Sum of Partial Credits Awarded / ".
-              "Total Number of Tries )</b>".
-              " <br><br>");
-    $r->rflush();
-    my $low=0;
-    my $up=$Count-$UpCnt;
-    my @UpList=();
-    my @LowList=();
-    $Count=0;
-    foreach my $key (sort(keys(%DiscFac))){ 
-	$Count++;    
-#        $r->print("$Count) $key <br>");
-
-	if ($low < $UpCnt || $Count > $up) {
-	    $low++;
-	    my $str=$DiscFac{$key};
-#            $r->print("$Count) $str <br>");
-	    foreach(split(/\:/,$str)){
-		if ($_) {
-		    if ($low<$UpCnt){push(@LowList,$_);}
-		    else {push(@UpList,$_);}
-		}
-	    }
-	}
-    }
-
-    my %Up=&ProcessDisc(@UpList);
-    my %Low=&ProcessDisc(@LowList);
-
-    my @list = ();
-    my $Useful;
-    my $UnUseful;
-    $p_count = 0;
-
-    foreach my $key( keys %CachData) { 
-	my @Temp=split(/\:/,$CachData{$key});
-	($UnUseful,$Useful)=split(/\>/,$Temp[0]);   
-	$list[$p_count]=$Useful.'&'.$CachData{$key};
-        $p_count++;
-    }
-
-    @list = sort MySort (@list);
-
-    my $Result = "\n".'<table border=2>';
-    $Result .= "\n".'<tr><th>P#</th>'; 
-    $Result .= "\n".'<th>'.$Header{0}.'</th>';
-    $Result .= "\n".'<th>'.'Discrimination Factor'.'</th>';
-    $Result .= "\n".'<th>'.'%Upper Award'.'</th>';
-    $Result .= "\n".'<th>'.'%Lower Award'.'</th>';
-    $Result .= "\n".'<th>'.'Upper Records'.'</th>';
-    $Result .= "\n".'<th>'.'Lower Records'.'</th>';
-    $Result .= "\n".'<th>'.'%Degree of Difficulty'.'</th>';
-    $Result .= "\n".'</tr>';    
-    $r->print( $Result );
-
-    for ( my $nIdx = 0; $nIdx < $p_count; $nIdx++ ) {
-	my( $Pre, $Post ) = split(/\&/,$list[$nIdx]); 
-	my ($Temp,$MxTries,$StdNo,$TotalTries,$YES,$Override,
-            $Wrng,$Avg,$SD,$Sk,$DoD,$res,$Prob)=split(/\:/,$Post);
-	my ($UpDis,$UpNo)=split(/\:/,$Up{$Prob});
-	my ($LwDis,$LwNo)=split(/\:/,$Low{$Prob});
-	$UpNo = ($UpNo) ? $UpNo : 0;
-	$LwNo = ($LwNo) ? $LwNo : 0;
-	my $U_Dis = sprintf("%.4f", $UpDis)*100;
-	my $L_Dis = sprintf("%.4f", $LwDis)*100;
-	my $DisFac = $UpDis - $LwDis;
-	my $_Dis = sprintf("%.4f", $DisFac)*100;
-        $r->print( "\n".'<tr>'.
-                   "\n".'<td>'.($nIdx+1).'</td>'.
-                   "\n".'<td>'.$Temp.'</td>'.
-                   "\n".'<td>'.$_Dis.'</td>'.
-                   "\n".'<td>'.$U_Dis.'</td>'.
-                   "\n".'<td>'.$L_Dis.'</td>'.
-                   "\n".'<td>'.$UpNo.'</td>'.
-                   "\n".'<td>'.$LwNo.'</td>'.
-                   "\n".'<td>'.$DoD.'</td>'.
-                   "\n".'</tr>' );
-    } 
-    $r->print("\n".'</table>');
-    $r->rflush();
+
+#######################################################
+#######################################################
+
+=pod
+
+=item Package Variables
+
+=item @FullClasslist The full classlist
+
+=item @Students The students we are concerned with for this invocation
+
+=item @Sections The sections available in this class
+
+=item $curr_student The student currently being examined
+
+=item $prev_student The student previous in the classlist
+
+=item $next_student The student next in the classlist
+
+=over
+
+=cut 
+
+#######################################################
+#######################################################
+#
+# Classlist variables
+#
+my $curr_student;
+my $prev_student;
+my $next_student;
+
+#######################################################
+#######################################################
+
+=pod
+
+=item &clear_classlist_variables()
+
+undef the following package variables:
+
+=over
+
+=item @FullClasslist
+
+=item @Students
+
+=item @Sections
+
+=item @SelectedSections
+
+=item %StudentData
+
+=item @StudentDataOrder
+
+=item @SelectedStudentData
+
+=item $curr_student
+
+=item $prev_student
+
+=item $next_student
+
+=back
+
+=cut
+
+#######################################################
+#######################################################
+sub clear_classlist_variables {
+    undef(@FullClasslist);
+    undef(@Students);
+    undef(@Sections);
+    undef(@SelectedSections);
+    undef(%StudentData);
+    undef(@SelectedStudentData);
+    undef($curr_student);
+    undef($prev_student);
+    undef($next_student);
 }
 
-sub CreateDiscFac {
+#######################################################
+#######################################################
+
+=pod
+
+=item &PrepareClasslist()
+
+Build up the classlist information.  The classlist information is kept in
+the following package variables:
+
+=over
+
+=item @FullClasslist
+
+=item @Students
+
+=item @Sections
+
+=item @SelectedSections
+
+=item %StudentData
+
+=item @SelectedStudentData
+
+=item $curr_student
+
+=item $prev_student
+
+=item $next_student
+
+=back
+
+$curr_student, $prev_student, and $next_student may not be defined, depending
+upon the calling context.
 
-    my $CacheDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
-                  "_$ENV{'user.domain'}_$cid\_statistics.db";
-    my $CachDisFac = "/home/httpd/perl/tmp/$ENV{'user.name'}".
-		     "_$ENV{'user.domain'}_$cid\_DiscFactor.db";
-
-    my $ptr='';
-#    $ptr .= '<br><b> Discrimination Criterion: &nbsp; </b>'."\n".
-#            '<select name="DisType"> <option '.$OpSelDis1.'>  Total Numebr of Correct Answers </option>'."\n".
-#	    '<option '.$OpSelDis2.'></option>Sum of Partial Awarded Credits / Total Number of Tries  </select> '."\n";		          
-    $ptr .= '<br><input type="submit" name="sort" '.
-            'value="Recalculate Discrimintion Factor" />';
-    $r->print($ptr);
-
-    if ((-e "$CacheDB")&&
-         ($ENV{'form.sort'} ne 'Recalculate Discrimintion Factor')) {
-	if (tie(%CachData,'GDBM_File',"$CacheDB",&GDBM_READER,0640)) {
-            tie(%DiscFac,'GDBM_File',$CachDisFac,&GDBM_READER,0640);
-            #&DiscriminationTable();
-	    &Classify(); 
-        } 
-        else {$r->print("Unable to tie hash to db file");}
-    }
-    else {
-	if (tie(%CachData,'GDBM_File',$CacheDB,&GDBM_WRCREAT,0640)) {
-	    tie(%DiscFac,'GDBM_File',$CachDisFac,&GDBM_WRCREAT,0640);
-	    foreach (keys %CachData) {delete $CachData{$_};}
-	    foreach (keys %DiscFac) {delete $DiscFac{$_};}
-	    $DiscFlag=1;
-	    &Build_Statistics();
-	    $DiscFlag=0;
-            &DiscriminationTable(); 
-	}
-        else {$r->print("Unable to tie hash to db file");}
-    }
-    untie(%CachData);
-    untie(%DiscFac);
-}	    
-
-
-# ------ Create different Student Report 
-sub StudentReport {
-    my ($sname,$sdom)=@_;
-    if ( $sname eq 'All Students' ) {
-	$r->print( '<h3><font color=blue>WARNING: 
-                    Please select a student</font></h3>' );
-	return;
-    }
-    my $shome=&Apache::lonnet::homeserver( $sname,$sdom );          
-    my $reply=&Apache::lonnet::reply('dump:'.$sdom.':'.$sname.':'.$cid,$shome );
-    my %result = ();
-    my $ResId;
-    my $Code;
-    my $Tries;
-    my $TotalTries = 0;
-    my $ParCr = 0;
-    my $Wrongs;
-    my %TempHash;
-    my $Version;
-    my $LatestVersion;
-    my $PtrTry='';
-    my $PtrCod='';
-    my $SetNo=0;
-    my $Str = "\n".'<table border=2>'.
-              "\n".'<tr>'.
-              "\n".'<th> # </th>'.
-	      "\n".'<th> Set Title </th>'.
-	      "\n".'<th> Results </th>'.
-	      "\n".'<th> Tries </th>'.
-	      "\n".'</tr>';
-    unless ($reply=~/^error\:/) {
-        map {
-            my ($name,$value)=split(/\=/,&Apache::lonnet::unescape($_));
-            $result{$name}=$value;
-        } split(/\&/,$reply);;
-        foreach $ResId (@cols) {
-	    if ( !$ResId ) {
-		my $Set=&Apache::lonnet::declutter($hash{'map_id_'.$1});
-		if ( $Set ) {
-		    $SetNo++;
-		    $Str .= "\n"."<tr>".
-			    "\n"."<td> $SetNo </td>".
-                            "\n"."<td> $Set </td>".
-                            "\n"."<td> $PtrCod </td>".
-                            "\n"."<td> $PtrTry</td>".
-                            "\n"."</tr>";
-		}
-		$PtrTry='';
-		$PtrCod='';
-		next; 
-	    }
-            $ResId=~/(\d+)\.(\d+)/;
-            my $Map = &Apache::lonnet::declutter( $hash{'map_id_'.$1} );
-            if ( $CurMap ne 'All Maps' ) {
-		my ( $ResMap, $NameMap ) = split(/\=/,$CurMap);
-		if ( $Map ne $ResMap ) { next; }
-	    }
-	    my $meta=$hash{'src_'.$ResId};
-	    my $PartNo = 0;
-	    undef %TempHash;
-	    map {
-		if ($_=~/^stores\_(\d+)\_tries$/) {
-                    my $Part=&Apache::lonnet::metadata($meta,$_.'.part');
-		    if ( $TempHash{"$Part"} eq '' ) { 
-			$TempHash{"$Part"} = $Part;
-			$TempHash{$PartNo}=$Part;
-			$TempHash{"$Part.Code"} = '-';  
-			$PartNo++;
-		    }
-		}
-            } split(/\,/,&Apache::lonnet::metadata($meta,'keys'));
-
-            my $Prob = $Map.'___'.$2.'___'.
-                       &Apache::lonnet::declutter( $hash{'src_'.$ResId} );
-            $Code='U';
-            $Tries = 0;
-            $Wrongs = 0;
-  	    $LatestVersion = $result{"version:$Prob"};       
-
-	    if ( $LatestVersion ) {
-		for ( my $Version=1; $Version<=$LatestVersion; $Version++ ) {
-		    my $vkeys = $result{"$Version:keys:$Prob"};
-		    my @keys = split(/\:/,$vkeys);		
-  
-		    foreach my $Key (@keys) {		  
-			if (($Key=~/\.(\w+)\.solved$/) && ($Key!~/^\d+\:/)) {
-			    my $Part = $1;
-			    $Tries = $result{"$Version:$Prob:resource.$Part.tries"};
-			    $TempHash{"$Part.Tries"} = ($Tries) ? $Tries : 0; 
-			    $TotalTries += $Tries;
-			    my $Val = $result{"$Version:$Prob:resource.$Part.solved"};
-			    if ( $Val eq 'correct_by_student' )
-                                { $Wrongs = $Tries - 1; $Code = 'Y'; } 
-			    elsif ( $Val eq 'correct_by_override' )
-                                { $Wrongs = $Tries - 1; $Code = 'y'; }                        
-			    elsif ( $Val eq 'incorrect_attempted' || 
-                                $Val eq 'incorrect_by_override' )
-		                { $Wrongs = $Tries; $Code = 'N'; }
-			    $TempHash{"$Part.Code"} = $Code;
-			    $TempHash{"$Part.Wrongs"} = $Wrongs;
-			}
-     		    }
-                } 
-		for ( my $n = 0; $n < $PartNo; $n++ ) {		  
-		    my $part = $TempHash{$n};
-		    if ($PtrTry ne '') {$PtrTry .= ',';}
-		    $PtrTry .= "$TempHash{$part.'.Tries'}";
-                    $PtrCod .= "$TempHash{$part.'.Code'}";    
-		}
+=cut
+
+#######################################################
+#######################################################
+sub PrepareClasslist {
+    my $r = shift;
+    my %Sections;
+    &clear_classlist_variables();
+    #
+    # Retrieve the classlist
+    my $cid  = $ENV{'request.course.id'};
+    my $cdom = $ENV{'course.'.$cid.'.domain'};
+    my $cnum = $ENV{'course.'.$cid.'.num'};
+    my ($classlist,$field_names) = &Apache::loncoursedata::get_classlist($cid,
+                                                                  $cdom,$cnum);
+    if (exists($ENV{'form.Section'})) {
+        if (ref($ENV{'form.Section'})) {
+            @SelectedSections = @{$ENV{'form.Section'}};
+        } elsif ($ENV{'form.Section'} !~ /^\s*$/) {
+            @SelectedSections = ($ENV{'form.Section'});
+        }
+    }
+    @SelectedSections = ('all') if (! @SelectedSections);
+    foreach (@SelectedSections) {
+        if ($_ eq 'all') {
+            @SelectedSections = ('all');
+        }
+    }
+    #
+    # Set up %StudentData
+    @StudentDataOrder = qw/fullname username domain id section status/;
+    foreach my $field (@StudentDataOrder) {
+        $StudentData{$field}->{'title'} = $field;
+        $StudentData{$field}->{'base_width'} = 
+                               scalar (my @Tmp = split(//,$field));
+        $StudentData{$field}->{'width'} = 
+                               $StudentData{$field}->{'base_width'};
+    }
+
+    #
+    # Process the classlist
+    while (my ($student,$student_data) = each (%$classlist)) {
+        my $studenthash = ();
+        for (my $i=0; $i< scalar(@$field_names);$i++) {
+            my $field = $field_names->[$i];
+            # Store the data
+            $studenthash->{$field}=$student_data->[$i];
+            # Keep track of the width of the fields
+            next if (! exists($StudentData{$field}));
+            my $length = scalar(my @Tmp1 = split(//,$student_data->[$i]));
+            if ($StudentData{$field}->{'width'} < $length) {
+                $StudentData{$field}->{'width'} = $length; 
+            }
+        }
+        push (@FullClasslist,$studenthash);
+        #
+        # Build up a list of sections
+        my $section = $studenthash->{'section'};
+        if (! defined($section) || $section =~/^\s*$/ || $section == -1) {
+            $studenthash->{'section'} = 'none';
+            $section = $studenthash->{'section'};
+        }
+        $Sections{$section}++;
+        #
+        # Only put in the list those students we are interested in
+        foreach my $sect (@SelectedSections) {
+            if (($sect eq 'all') || ($section eq $sect)) {
+                push (@Students,$studenthash);
+                last;
             }
-	    else { 
-		for(my $n=0; $n<$PartNo; $n++) { 
-		    if ($PtrTry ne '') {$PtrTry .= ',';}
-		    $PtrTry .= "0";
-                    $PtrCod .= "-"; 
-		}
-	    }
         }
     }
-    $Str .= "\n".'</table>';
-    $r->print($Str);
-    $r->rflush();
+    #
+    # Put the consolidated section data in the right place
+    @Sections = sort {$a cmp $b} keys(%Sections);
+    unshift(@Sections,'all'); # Put 'all' at the front of the list
+    #
+    # Sort the Students
+    my $sortby = 'fullname';
+    $sortby = $ENV{'form.sort'} if (exists($ENV{'form.sort'}));
+    my @TmpStudents = sort { $a->{$sortby} cmp $b->{$sortby} ||
+                             $a->{'fullname'} cmp $b->{'fullname'} } @Students;
+    @Students = @TmpStudents;
+    # 
+    # Now deal with that current student thing....
+    if (exists($ENV{'form.StudentAssessmentStudent'})) {
+        my ($current_uname,$current_dom) = 
+            split(':',$ENV{'form.StudentAssessmentStudent'});
+        my $i;
+        for ($i = 0; $i<=$#Students; $i++) {
+            next if (($Students[$i]->{'username'} ne $current_uname) || 
+                     ($Students[$i]->{'domain'}   ne $current_dom));
+            $curr_student = $Students[$i];
+            last; # If we get here, we have our student.
+        }
+        if ($i == 0) {
+            $prev_student = 'none';
+        } else {
+            $prev_student = $Students[$i-1];
+        }
+        if ($i == $#Students) {
+            $next_student = 'none';
+        } else {
+            $next_student = $Students[$i+1];
+        }
+    }
+    #
+    if (exists($ENV{'form.StudentData'})) {
+        if (ref($ENV{'form.StudentData'}) eq 'ARRAY') {
+            @SelectedStudentData = @{$ENV{'form.StudentData'}};
+        } else {
+            @SelectedStudentData = ($ENV{'form.StudentData'});
+        }
+    } else {
+        @SelectedStudentData = ('fullname');
+    }
+    foreach (@SelectedStudentData) {
+        if ($_ eq 'all') {
+            @SelectedStudentData = ('all');
+            last;
+        }
+    }
+    #
+    return;
 }
 
+#######################################################
+#######################################################
+
+=pod
+
+=item &current_student()
 
+Returns a pointer to a hash containing data about the currently
+selected student.
 
+=cut
 
-# ------------------------------------------- Prepare Statistics Table
-sub PreStatTable {
-    my $CacheDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
-                  "_$ENV{'user.domain'}_$cid\_statistics.db";
-    my $GraphDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
-                  "_$ENV{'user.domain'}_$cid\_graph.db";
-    my $CachDisFac = "/home/httpd/perl/tmp/$ENV{'user.name'}".
-		     "_$ENV{'user.domain'}_$cid\_DiscFactor.db";
-    $r->print('<br><input type="submit" name="sort" value="Recalculate Statistics" />');
-
-    my $Ptr = '';
-
-    $Ptr .= '<br><b> Sorting Type: &nbsp; </b>'."\n".
-            '<select name="order"> <option '.$OpSel1.' >Ascending</option>'."\n".
-	    '<option '.$OpSel2.'>Descending</option> </select> '."\n";
-    $Ptr .= '&nbsp;&nbsp;&nbsp;';
-    $Ptr .= '<input type="submit" name="sort" value="DoDiff Graph" />'."\n";
-    $Ptr .= '&nbsp;&nbsp;&nbsp;';
-    $Ptr .= '<input type="submit" name="sort" value="%Wrong Graph" />'."\n";
-
-    $Ptr .= '<pre>'.
-    '  #Stdnts: Total Number of Students opened the problem.<br>'. 
-    '  Tries  : Total Number of Tries for solving the problem.<br>'. 
-    '  Mod    : Maximunm Number of Tries for solving the problem.<br>'. 
-    '  Mean   : Average Number of the tries. [ Tries / #Stdns ]<br>'.
-    '  #YES   : Number of students solved the problem correctly.<br>'. 
-    '  #yes   : Number of students solved the problem by override.<br>'.
-    '  %Wrng  : Percentage of students tried to solve the problem but'.
-    ' still incorrect. [ 100*((#Stdnts-(#YES+#yes))/#Stdnts) ]<br>'.
-    '  S.D.   : Standard Deviation of the tries.'.
-    '[ sqrt(sum((Xi - Mean)^2)) / (#Stdnts-1)'.
-    ' where Xi is every student\'s tries ]<br>'.
-    '  Skew.  : Skewness of the students tries.'.
-    ' [ (sqrt( sum((Xi - Mean)^3) / #Stdnts)) / (S.D.^3) ]<br>'.
-#    '  DoDiff : Degree of Difficulty of the problem. [ Tries/(#YES+#yes+0.1) ]<br>'.
-    '  DoDiff : Degree of Difficulty of the problem. [ 1 - ((#YES+#yes) / Tries) ]<br>'.
-#    '  Dis.F. : Discrimination Factor. [ Sum of Partial Credits Awarded / Total Number of Tries in %27 upper and lower students]</b>'.	
-            '</pre>';
-
-    $r->print($Ptr);
-    $r->rflush();	
-		      
-    my $Result = "\n".'<table border=2>';
-    $Result .= '<tr><th>P#</th>'."\n";
-    for ( my $nIdx=0; $nIdx < 12; $nIdx++ ) { 
-	$Result .= '<th>'.'<input type="submit" name="sort" value="'.
-                   $Header{$nIdx}.'" />'.'</th>'."\n";
+#######################################################
+#######################################################
+sub current_student { 
+    if (defined($curr_student)) {
+        return $curr_student;
+    } else {
+        return 'All Students';
     }
-    $Result .= "\n".'</tr>'."\n";    
-    $r->print( $Result );
+}
+
+#######################################################
+#######################################################
+
+=pod
+
+=item &previous_student()
+
+Returns a pointer to a hash containing data about the student prior
+in the list of students.  Or something.  
+
+=cut
+
+#######################################################
+#######################################################
+sub previous_student { 
+    if (defined($prev_student)) {
+        return $prev_student;
+    } else {
+        return 'No Student Selected';
+    }
+}
+
+#######################################################
+#######################################################
+
+=pod
+
+=item &next_student()
+
+Returns a pointer to a hash containing data about the next student
+to be viewed.
+
+=cut
+
+#######################################################
+#######################################################
+sub next_student { 
+    if (defined($next_student)) {
+        return $next_student;
+    } else {
+        return 'No Student Selected';
+    }
+}
+
+#######################################################
+#######################################################
+
+=pod
+
+=item &clear_sequence_variables()
+
+=cut
+
+#######################################################
+#######################################################
+sub clear_sequence_variables {
+    undef($top_map);
+    undef(@Sequences);
+    undef(@Assessments);
+}
+
+#######################################################
+#######################################################
+
+=pod
+
+=item &SetSelectedMaps($elementname)
+
+Sets the @SelectedMaps array from $ENV{'form.'.$elementname};
+
+=cut
+
+#######################################################
+#######################################################
+sub SetSelectedMaps {
+    my $elementname = shift;
+    if (exists($ENV{'form.'.$elementname})) {
+        if (ref($ENV{'form.'.$elementname})) {
+            @SelectedMaps = @{$ENV{'form.'.$elementname}};
+        } else {
+            @SelectedMaps = ($ENV{'form.'.$elementname});
+        }
+    } else {
+        @SelectedMaps = ('all');
+    }
+}
+
+#######################################################
+#######################################################
+
+=pod
+
+=item &PrepareCourseData($r)
+
+=cut
+
+#######################################################
+#######################################################
+sub PrepareCourseData {
+    my ($r) = @_;
+    &clear_sequence_variables();
+    my ($top,$sequences,$assessments) = 
+        &Apache::loncoursedata::get_sequence_assessment_data();
+    if (! defined($top) || ! ref($top)) {
+        # There has been an error, better report it
+        &Apache::lonnet::logthis('top is undefined');
+        return;
+    }
+    $top_map = $top if (ref($top));
+    @Sequences = @{$sequences} if (ref($sequences) eq 'ARRAY');
+    @Assessments = @{$assessments} if (ref($assessments) eq 'ARRAY');
+    #
+    # Compute column widths
+    foreach my $seq (@Sequences) {
+        my $name_length = scalar(my @Tmp1 = split(//,$seq->{'title'}));
+        my $num_parts = $seq->{'num_assess_parts'};
+        #
+        # The number of columns needed for the summation text: 
+        #    " 1/5" = 1+3 columns, " 10/99" = 1+5 columns
+        my $sum_length = 1+1+2*(scalar(my @Tmp2 = split(//,$num_parts)));
+        my $num_col = $num_parts+$sum_length;
+        if ($num_col < $name_length) {
+            $num_col = $name_length;
+        }
+        $seq->{'base_width'} = $name_length;
+        $seq->{'width'} = $num_col;
+    }
+    return;
+}
+
+#######################################################
+#######################################################
+
+=pod
+
+=item &log_sequence($sequence,$recursive,$padding)
+
+Write data about the sequence to a logfile.  If $recursive is not
+undef the data is written recursively.  $padding is used for recursive
+calls.
+
+=cut
+
+#######################################################
+#######################################################
+sub log_sequence {
+    my ($seq,$recursive,$padding) = @_;
+    $padding = '' if (! defined($padding));
+    if (ref($seq) ne 'HASH') {
+        &Apache::lonnet::logthis('log_sequence passed bad sequnce');
+        return;
+    }
+    &Apache::lonnet::logthis($padding.'sequence '.$seq->{'title'});
+    while (my($key,$value) = each(%$seq)) {
+        next if ($key eq 'contents');
+        if (ref($value) eq 'ARRAY') {
+            for (my $i=0;$i< scalar(@$value);$i++) {
+                &Apache::lonnet::logthis($padding.$key.'['.$i.']='.
+                                         $value->[$i]);
+            }
+        } else {
+            &Apache::lonnet::logthis($padding.$key.'='.$value);
+        }
+    }
+    if (defined($recursive)) {
+        &Apache::lonnet::logthis($padding.'-'x20);
+        &Apache::lonnet::logthis($padding.'contains:');
+        foreach my $item (@{$seq->{'contents'}}) {
+            if ($item->{'type'} eq 'container') {
+                &log_sequence($item,$recursive,$padding.'    ');
+            } else {
+                &Apache::lonnet::logthis($padding.'title = '.$item->{'title'});
+                while (my($key,$value) = each(%$item)) {
+                    next if ($key eq 'title');
+                    if (ref($value) eq 'ARRAY') {
+                        for (my $i=0;$i< scalar(@$value);$i++) {
+                            &Apache::lonnet::logthis($padding.$key.'['.$i.']='.
+                                                     $value->[$i]);
+                        }
+                    } else {
+                        &Apache::lonnet::logthis($padding.$key.'='.$value);
+                    }
+                }
+            }
+        }
+        &Apache::lonnet::logthis($padding.'end contents of '.$seq->{'title'});
+        &Apache::lonnet::logthis($padding.'-'x20);
+    }
+    return;
+}
+
+##############################################
+##############################################
+
+=pod 
+
+=item &StudentDataSelect($elementname,$status,$numvisible,$selected)
+
+Returns html for a selection box allowing the user to choose one (or more) 
+of the fields of student data available (fullname, username, id, section, etc)
+
+=over 4
+
+=item $elementname The name of the HTML form element
+
+=item $status 'multiple' or 'single' selection box
+
+=item $numvisible The number of options to be visible
+
+=back
+
+=cut
+
+##############################################
+##############################################
+sub StudentDataSelect {
+    my ($elementname,$status,$numvisible)=@_;
+    if ($numvisible < 1) {
+        return;
+    }
+    #
+    # Build the form element
+    my $Str = "\n";
+    $Str .= '<select name="'.$elementname.'" ';
+    if ($status ne 'single') {
+        $Str .= 'multiple="true" ';
+    }
+    $Str .= 'size="'.$numvisible.'" >'."\n";
+    #
+    # Deal with 'all'
+    $Str .= '    <option value="all" ';
+    foreach (@SelectedStudentData) {
+        if ($_ eq 'all') {
+            $Str .= 'selected ';
+            last;
+        }
+    }
+    $Str .= ">all</option>\n";
+    #
+    # Loop through the student data fields
+    foreach my $item (@StudentDataOrder) {
+        $Str .= '    <option value="'.$item.'" ';
+        foreach (@SelectedStudentData) {
+            if ($item eq $_ ) {
+                $Str .= 'selected ';
+                last;
+            }
+        }
+        $Str .= '>'.$item."</option>\n";
+    }
+    $Str .= "</select>\n";
+    return $Str;
+}
+
+##############################################
+##############################################
+
+=pod 
+
+=item &MapSelect($elementname,$status,$numvisible,$restriction) 
+
+Returns html for a selection box allowing the user to choose one (or more) 
+of the sequences in the course.  The values of the sequences are the symbs.
+If the top sequence is selected, the value 'top' will result.
+
+=over 4
+
+=item $elementname The name of the HTML form element
+
+=item $status 'multiple' or 'single' selection box
+
+=item $numvisible The number of options to be visible
+
+=item $restriction Code reference to subroutine which returns true or 
+false.  The code must expect a reference to a sequence data structure.
+
+=back
+
+=cut
+
+##############################################
+##############################################
+sub MapSelect {
+    my ($elementname,$status,$numvisible,$restriction)=@_;
+    if ($numvisible < 1) {
+        return;
+    }
+    #
+    # Set up array of selected items
+    &SetSelectedMaps($elementname);
+    #
+    # Set up the restriction call
+    if (! defined($restriction)) {
+        $restriction = sub { 1; };
+    }
+    #
+    # Build the form element
+    my $Str = "\n";
+    $Str .= '<select name="'.$elementname.'" ';
+    if ($status ne 'single') {
+        $Str .= 'multiple="true" ';
+    }
+    $Str .= 'size="'.$numvisible.'" >'."\n";
+    #
+    # Deal with 'all'
+    foreach (@SelectedMaps) {
+        if ($_ eq 'all') {
+            @SelectedMaps = ('all');
+            last;
+        }
+    }
+    #
+    # Put in option for 'all'
+    $Str .= '    <option value="all" ';
+    foreach (@SelectedMaps) {
+        if ($_ eq 'all') {
+            $Str .= 'selected ';
+            last;
+        }
+    }
+    $Str .= ">all</option>\n";
+    #
+    # Loop through the sequences
+    foreach my $seq (@Sequences) {
+        next if (! $restriction->($seq));
+        $Str .= '    <option value="'.$seq->{'symb'}.'" ';
+        foreach (@SelectedMaps) {
+            if ($seq->{'symb'} eq $_) {
+                $Str .= 'selected ';
+                last;
+            }
+        }
+        $Str .= '>'.$seq->{'title'}."</option>\n";
+    }
+    $Str .= "</select>\n";
+    return $Str;
+}
+
+##############################################
+##############################################
+
+=pod 
+
+=item &SectionSelect($elementname,$status,$numvisible) 
+
+Returns html for a selection box allowing the user to choose one (or more) 
+of the sections in the course.  
+
+=over 4
+
+=item $elementname The name of the HTML form element
+
+=item $status 'multiple' or 'single' selection box
+
+=item $numvisible The number of options to be visible
+
+=item $selected Array ref to the names of the already selected sections.
+If undef, $ENV{'form.'.$elementname} is used.  
+If $ENV{'form.'.$elementname} is also empty, none will be selected.
+
+=item $restriction Code reference to subroutine which returns true or 
+false.  The code must expect a reference to a sequence data structure.
+
+=back
+
+=cut
+
+##############################################
+##############################################
+sub SectionSelect {
+    my ($elementname,$status,$numvisible)=@_;
+    if ($numvisible < 1) {
+        return;
+    }
+    #
+    # Build the form element
+    my $Str = "\n";
+    $Str .= '<select name="'.$elementname.'" ';
+    if ($status ne 'single') {
+        $Str .= 'multiple="true" ';
+    }
+    $Str .= 'size="'.$numvisible.'" >'."\n";
+    #
+    # Loop through the sequences
+    foreach my $s (@Sections) {
+        $Str .= '    <option value="'.$s.'" ';
+        foreach (@SelectedSections) {
+            if ($s eq $_) {
+                $Str .= 'selected ';
+                last;
+            }
+        }
+        $Str .= '>'.$s."</option>\n";
+    }
+    $Str .= "</select>\n";
+    return $Str;
+}
+
+##############################################
+##############################################
+
+sub CheckFormElement {
+    my ($cache, $ENVName, $cacheName, $default)=@_;
+
+    if(defined($ENV{'form.'.$ENVName})) {
+        $cache->{$cacheName} = $ENV{'form.'.$ENVName};
+    } elsif(!defined($cache->{$cacheName})) {
+        $cache->{$cacheName} = $default;
+    } else {
+        $ENV{'form.'.$ENVName} = $cache->{$cacheName};
+    }
+    return;
+}
+
+sub ProcessFormData{
+    my ($cache)=@_;
+
+    $cache->{'reportKey'} = 'false';
+
+    &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},
+                                            ['download',
+                                             'reportSelected',
+                                             'StudentAssessmentStudent',
+                                             'ProblemStatisticsSort']);
+    &CheckFormElement($cache, 'DownloadAll', 'DownloadAll', 'false');
+    if ($cache->{'DownloadAll'} ne 'false') {
+        # Clean the hell out of that cache!
+        # We cannot untie the hash at this scope (stupid libgd :( )
+        # So, remove every single key.  What a waste of time....
+        # Of course, if you are doing this you are probably resigned
+        # to waiting a while.
+        &Apache::lonnet::logthis("Cleaning out the cache file");
+        while (my ($key,undef)=each(%$cache)) {
+            next if ($key eq 'DownloadAll');
+            delete($cache->{$key});
+        }
+    }
+    &CheckFormElement($cache, 'Status', 'Status', 'Active');
+    &CheckFormElement($cache, 'postdata', 'reportSelected', 'Class list');
+    &CheckFormElement($cache, 'reportSelected', 'reportSelected', 
+                      'Class list');
+    $cache->{'reportSelected'} = 
+        &Apache::lonnet::unescape($cache->{'reportSelected'});
+    &CheckFormElement($cache, 'sort', 'sort', 'fullname');
+    &CheckFormElement($cache, 'download', 'download', 'false');
+    &CheckFormElement($cache, 'StatisticsMaps', 
+                      'StatisticsMaps', 'All Maps');
+    &CheckFormElement($cache, 'StatisticsProblemSelect',
+		      'StatisticsProblemSelect', 'All Problems');
+    &CheckFormElement($cache, 'StatisticsPartSelect',
+		      'StatisticsPartSelect', 'All Parts');
+    if(defined($ENV{'form.Section'})) {
+        my @sectionsSelected = (ref($ENV{'form.Section'}) ?
+                               @{$ENV{'form.Section'}} :
+                                ($ENV{'form.Section'}));
+        $cache->{'sectionsSelected'} = join(':', @sectionsSelected);
+    } elsif(!defined($cache->{'sectionsSelected'})) {
+        $cache->{'sectionsSelected'} = $cache->{'sectionList'};
+    }
+
+    # student assessment
+    if(defined($ENV{'form.CreateStudentAssessment'}) ||
+       defined($ENV{'form.NextStudent'}) ||
+       defined($ENV{'form.PreviousStudent'})) {
+        $cache->{'reportSelected'} = 'Student Assessment';
+    }
+    if(defined($ENV{'form.NextStudent'})) {
+        $cache->{'StudentAssessmentMove'} = 'next';
+    } elsif(defined($ENV{'form.PreviousStudent'})) {
+        $cache->{'StudentAssessmentMove'} = 'previous';
+    } else {
+        $cache->{'StudentAssessmentMove'} = 'selected';
+    }
+    &CheckFormElement($cache, 'StudentAssessmentStudent', 
+                      'StudentAssessmentStudent', 'All Students');
+    $cache->{'StudentAssessmentStudent'} = 
+        &Apache::lonnet::unescape($cache->{'StudentAssessmentStudent'});
+    &CheckFormElement($cache, 'DefaultColumns', 'DefaultColumns', 'false');
+
+    # Problem analysis
+    &CheckFormElement($cache, 'Interval', 'Interval', '1');
+
+    # ProblemStatistcs
+    &CheckFormElement($cache, 'DisplayCSVFormat',
+                      'DisplayFormat', 'Display Table Format');
+    &CheckFormElement($cache, 'ProblemStatisticsAscend',
+                      'ProblemStatisticsAscend', 'Ascending');
+    &CheckFormElement($cache, 'ProblemStatisticsSort',
+                      'ProblemStatisticsSort', 'Homework Sets Order');
+    &CheckFormElement($cache, 'DisplayLegend', 'DisplayLegend', 
+		      'Hide Legend');
+    &CheckFormElement($cache, 'SortProblems', 'SortProblems', 
+                      'Sort Within Sequence');
+
+    # Search only form elements
+    my @headingColumns=();
+    my @sequenceColumns=();
+    my $foundColumn = 0;
+    if(defined($ENV{'form.ReselectColumns'})) {
+        my @reselected = (ref($ENV{'form.ReselectColumns'}) ? 
+                          @{$ENV{'form.ReselectColumns'}}
+                          : ($ENV{'form.ReselectColumns'}));
+        foreach (@reselected) {
+            if(/HeadingColumn/) {
+                push(@headingColumns, $_);
+                $foundColumn = 1;
+            } elsif(/SequenceColumn/) {
+                push(@sequenceColumns, $_);
+                $foundColumn = 1;
+            }
+        }
+    }
+
+    $cache->{'reportKey'} = 'false';
+    if($cache->{'reportSelected'} eq 'Analyze') {
+        $cache->{'reportKey'} = 'Analyze';
+    } elsif($cache->{'reportSelected'} eq 'DoDiffGraph') {
+        $cache->{'reportKey'} = 'DoDiffGraph';
+    } elsif($cache->{'reportSelected'} eq 'PercentWrongGraph') {
+        $cache->{'reportKey'} = 'PercentWrongGraph';
+    }
+
+    if(defined($ENV{'form.DoDiffGraph'})) {
+        $cache->{'reportSelected'} = 'DoDiffGraph';
+        $cache->{'reportKey'} = 'DoDiffGraph';
+    } elsif(defined($ENV{'form.PercentWrongGraph'})) {
+        $cache->{'reportSelected'} = 'PercentWrongGraph';
+        $cache->{'reportKey'} = 'PercentWrongGraph';
+    }
+
+    foreach (keys(%ENV)) {
+        if(/form\.Analyze/) {
+            $cache->{'reportSelected'} = 'Analyze';
+            $cache->{'reportKey'} = 'Analyze';
+            my $data;
+            (undef, $data)=split(':::', $_);
+            $cache->{'AnalyzeInfo'}=$data;
+        } elsif(/form\.HeadingColumn/) {
+            my $value = $_;
+            $value =~ s/form\.//;
+            push(@headingColumns, $value);
+            $foundColumn=1;
+        } elsif(/form\.SequenceColumn/) {
+            my $value = $_;
+            $value =~ s/form\.//;
+            push(@sequenceColumns, $value);
+            $foundColumn=1;
+        }
+    }
+
+    if($foundColumn) {
+        $cache->{'HeadingsFound'} = join(':', @headingColumns);
+        $cache->{'SequencesFound'} = join(':', @sequenceColumns);;
+    }
+    if(!defined($cache->{'HeadingsFound'}) || 
+       $cache->{'DefaultColumns'} ne 'false') {
+        $cache->{'HeadingsFound'}='HeadingColumnFull Name';
+    }
+    if(!defined($cache->{'SequencesFound'}) ||
+       $cache->{'DefaultColumns'} ne 'false') {
+        $cache->{'SequencesFound'}='All Sequences';
+    }
+    $cache->{'DefaultColumns'} = 'false';
+
+    return;
+}
+
+##################################################
+##################################################
+
+=pod
+
+=item &SortStudents()
+
+Determines which students to display and in which order.  Which are 
+displayed are determined by their status(active/expired).  The order
+is determined by the sort button pressed (default to username).  The
+type of sorting is username, lastname, or section.
+
+=over 4
+
+Input: $students, $CacheData
+
+$students: A array pointer to a list of students (username:domain)
+
+$CacheData: A pointer to the hash tied to the cached data
+
+Output: \@order
+
+@order: An ordered list of students (username:domain)
+
+=back
+
+=cut
+
+sub SortStudents {
+    my ($cache)=@_;
+
+    my @students = split(':::',$cache->{'NamesOfStudents'});
+    my @sorted1Students=();
+    foreach (@students) {
+        if($cache->{'Status'} eq 'Any' || 
+           $cache->{$_.':Status'} eq $cache->{'Status'}) {
+            push(@sorted1Students, $_);
+        }
+    }
+
+    my $sortBy = '';
+    if(defined($cache->{'sort'})) {
+        $sortBy = ':'.$cache->{'sort'};
+    } else {
+        $sortBy = ':fullname';
+    }
+    my @order = sort { lc($cache->{$a.$sortBy}) cmp lc($cache->{$b.$sortBy}) ||
+                       lc($cache->{$a.':fullname'}) cmp lc($cache->{$b.':fullname'}) } 
+                @sorted1Students;
+
+    return \@order;
+}
+
+=pod
+
+=item &SpaceColumns()
+
+Determines the width of all the columns in the chart.  It is based on
+the max of the data for that column and its header.
+
+=over 4
+
+Input: $students, $studentInformation, $headings, $ChartDB
+
+$students: An array pointer to a list of students (username:domain)
+
+$studentInformatin: The type of data for the student information.  It is
+used as part of the key in $CacheData.
+
+$headings: The name of the student information columns.
+
+$ChartDB: The name of the cache database which is opened for read/write.
+
+Output: None - All data stored in cache.
+
+=back
+
+=cut
+
+sub SpaceColumns {
+    my ($students,$studentInformation,$headings,$cache)=@_;
+
+    # Initialize Lengths
+    for(my $index=0; $index<(scalar @$headings); $index++) {
+        my @titleLength=split(//,$headings->[$index]);
+        $cache->{$studentInformation->[$index].':columnWidth'}=
+            scalar @titleLength;
+    }
+
+    foreach my $name (@$students) {
+        foreach (@$studentInformation) {
+            my @dataLength=split(//,$cache->{$name.':'.$_});
+            my $length=(scalar @dataLength);
+            if($length > $cache->{$_.':columnWidth'}) {
+                $cache->{$_.':columnWidth'}=$length;
+            }
+        }
+    }
+
+    return;
+}
+
+sub PrepareData {
+    my ($c, $cacheDB, $studentInformation, $headings,$r)=@_;
+
+    # Test for access to the cache data
+    my $courseID=$ENV{'request.course.id'};
+    my $isRecalculate=0;
+    if(defined($ENV{'form.Recalculate'})) {
+        $isRecalculate=1;
+    }
+
+    my $isCached = &Apache::loncoursedata::TestCacheData($cacheDB,
+                                                         $isRecalculate);
+    if($isCached < 0) {
+        return "Unable to tie hash to db file.";
+    }
+
+    # Download class list information if not using cached data
+    my %cache;
+    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT(),0640)) {
+        return "Unable to tie hash to db file.";
+    }
+
+#    if(!$isCached) {
+        my $processTopResourceMapReturn=
+            &Apache::loncoursedata::ProcessTopResourceMap(\%cache, $c);
+        if($processTopResourceMapReturn ne 'OK') {
+            untie(%cache);
+            return $processTopResourceMapReturn;
+        }
+ #   }
+
+    if($c->aborted()) {
+        untie(%cache);
+        return 'aborted'; 
+    }
+
+    my $classlist=&Apache::loncoursedata::DownloadClasslist($courseID,
+                                                $cache{'ClasslistTimestamp'},
+                                                $c);
+    foreach (keys(%$classlist)) {
+        if(/^(con_lost|error|no_such_host)/i) {
+            untie(%cache);
+            return "Error getting student data.";
+        }
+    }
+
+    if($c->aborted()) {
+        untie(%cache);
+        return 'aborted'; 
+    }
+
+    # Active is a temporary solution, remember to change
+    Apache::loncoursedata::ProcessClasslist(\%cache,$classlist,$courseID,$c);
+    if($c->aborted()) {
+        untie(%cache);
+        return 'aborted'; 
+    }
+
+    &ProcessFormData(\%cache);
+    my $students = &SortStudents(\%cache);
+    &SpaceColumns($students, $studentInformation, $headings, \%cache);
+    $cache{'updateTime:columnWidth'}=24;
+
+    my $download = $cache{'download'};
+    my $downloadAll = $cache{'DownloadAll'};
+    my @allStudents=();
+    if($download ne 'false') {
+        $cache{'download'} = 'false';
+    } elsif($downloadAll ne 'false') {
+        $cache{'DownloadAll'} = 'false';
+        if($downloadAll eq 'sorted') {
+            @allStudents = @$students;
+        } else {
+            @allStudents = split(':::', $cache{'NamesOfStudents'});
+        }
+    }
+
+    untie(%cache);
+
+    if($download ne 'false') {
+        my @who = ($download);
+        if(&Apache::loncoursedata::DownloadStudentCourseData(\@who, 'false',
+                                                             $cacheDB, 'true',
+                                                             'false', $courseID,
+                                                             $r, $c) ne 'OK') {
+            return 'Stop at download individual';
+        }
+    } elsif($downloadAll ne 'false') {
+        if(&Apache::loncoursedata::DownloadStudentCourseData(\@allStudents,
+                                                             'false',
+                                                             $cacheDB, 'true',
+                                                             'true', $courseID,
+                                                             $r, $c) ne 'OK') {
+            return 'Stop at download all';
+        }
+    }
+
+    return ('OK', $students);
+}
+
+sub DisplayClasslist {
+    my ($r)=@_;
+    #
+    my @Fields = ('fullname','username','domain','id','section');
+    #
+    my $Str='';
+    $Str .= '<table border="0"><tr><td bgcolor="#777777">'."\n";
+    $Str .= '<table border="0" cellpadding="3"><tr bgcolor="#e6ffff">'."\n";
+    foreach my $field (@Fields) {
+        $Str .= '<th><a href="/adm/statistics?sort='.$field.'">'.$field.
+            '</a></th>';
+    }
+    $Str .= '</tr>'."\n";
+    #
+    my $alternate = 0;
+    foreach my $student (@Students) {
+        my $sname = $student->{'username'}.':'.$student->{'domain'};
+        if($alternate) {
+            $Str .= '<tr bgcolor="#ffffe6">';
+        } else {
+            $Str .= '<tr bgcolor="#ffffc6">';
+        }
+        $alternate = ($alternate + 1) % 2;
+        #
+        foreach my $field (@Fields) {
+            $Str .= '<td>';
+            if ($field eq 'fullname') {
+                $Str .= '<a href="/adm/statistics?reportSelected=';
+                $Str .= &Apache::lonnet::escape('Student Assessment');
+                $Str .= '&StudentAssessmentStudent=';
+                $Str .= &Apache::lonnet::escape($sname).'">';
+                $Str .= $student->{$field}.'&nbsp';
+                $Str .= '</a>';
+            } else {
+                $Str .= $student->{$field};
+            }
+            $Str .= '</td>';
+        }
+        $Str .= "</tr>\n";
+    }
+    $Str .= '</table></td></tr></table>'."\n";
+    #
+    $r->print($Str);
     $r->rflush();
+    #
+    return;
+}
+
+sub BuildClasslist {
+    my ($cacheDB,$students,$studentInformation,$headings,$r)=@_;
 
-    if ((-e "$CacheDB")&&($ENV{'form.sort'} ne 'Recalculate Statistics')) {
-	if (tie(%CachData,'GDBM_File',"$CacheDB",&GDBM_READER,0640)) {
-	    tie(%GraphDat,'GDBM_File',$GraphDB,&GDBM_WRCREAT,0640);
-	    &Cache_Statistics();
-        }
-        else {
-	    $r->print("Unable to tie hash to db file");
-        }
-    }
-    else {
-	if (tie(%CachData,'GDBM_File',$CacheDB,&GDBM_WRCREAT,0640)) {
-	    tie(%DiscFac,'GDBM_File',$CachDisFac,&GDBM_WRCREAT,0640);
-	    tie(%GraphDat,'GDBM_File',$GraphDB,&GDBM_WRCREAT,0640);
-	    foreach (keys %DiscFac) {delete $CachData{$_};}
-	    foreach (keys %CachData) {delete $CachData{$_};}
-	    $DiscFlag=0;
-	    &Build_Statistics();
-	}
-        else {
-	    $r->print("Unable to tie hash to db file");
-        }
-    }
-    #$r->print('Total instances of the problems : '.($p_count*($#students+1)));
-
-    untie(%CachData);
-    untie(%GraphDat);
-    untie(%DiscFac);
-
-    $r->print("\n".'</table>'."\n");
-    $r->rflush();        
-}
-
-
-# ------------------------------------- Find the section of student in a course
-
-sub usection {
-    my ($udom,$unam,$courseid)=@_;
-    $courseid=~s/\_/\//g;
-    $courseid=~s/^(\w)/\/$1/;
-    map {
-        my ($key,$value)=split(/\=/,$_);
-        $key=&Apache::lonnet::unescape($key);
-        if ($key=~/^$courseid(?:\/)*(\w+)*\_st$/) {
-            my $section=$1;
-            if ($key eq $courseid.'_st') { $section=''; }
-	    my ($dummy,$end,$start)=split(/\_/,&Apache::lonnet::unescape($value));
-            $section=($section) ? $section : '(none)';
-            $section=(int($section)) ? int($section) : $section;
-#            $r->print($unam.'...'.$section.'<br>');
-	    return $section;
-        }
-    } split(/\&/,&Apache::lonnet::reply('dump:'.$udom.':'.$unam.':roles',
-                        &Apache::lonnet::homeserver($unam,$udom)));
-    return '';
-}
-
-
-# ------ Dump the Student's DB file and handling the data for statistics table 
-
-sub ExtractStudentData {
-    my ($student,$coid)=@_;
-    my ($sname,$sdom) = split( /\:/, $student );
-    my $shome=&Apache::lonnet::homeserver( $sname,$sdom );          
-    my $reply=&Apache::lonnet::reply('dump:'.$sdom.':'.$sname.':'.$coid,$shome );
-    my %result = ();
-    my $ResId;
-    my $Dis = '';
-    my $Code;
-    my $Tries;
-    my $ParCr;
-    my $TotalTries = 0;
-    my $TotalOpend = 0;
-    my $ProbSolved = 0;
-    my $ProbTot = 0;
-    my $TimeTot = 0;
-    my $TotParCr = 0;
-    my $Wrongs;
-    my %TempHash;
-    my $Version;
-    my $LatestVersion;
-    my $SecLimit;
-    my $MapLimit;
-    unless ($reply=~/^error\:/) {
-        map {
-            my ($name,$value)=split(/\=/,&Apache::lonnet::unescape($_));
-            $result{$name}=$value;
-#$r->print($name.'='.$value.'<br>');
-        } split(/\&/,$reply);
-        foreach $ResId (@cols) {
-	    if ( !$ResId ) { next; }
-            $ResId=~/(\d+)\.(\d+)/;
-            my $Map = &Apache::lonnet::declutter( $hash{'map_id_'.$1} );
-            if ( $CurMap ne 'All Maps' ) {
-		my ( $ResMap, $NameMap ) = split(/\=/,$CurMap);
-		if ( $Map ne $ResMap ) { next; }
-	    }
-	    my $meta=$hash{'src_'.$ResId};
-	    my $PartNo = 0;
-	    $Dis .= ':';
-	    undef %TempHash;
-	    map {
-		if ($_=~/^stores\_(\d+)\_tries$/) {
-                    my $Part=&Apache::lonnet::metadata($meta,$_.'.part');
-		    if ( $TempHash{"$Part"} eq '' ) { 
-			$TempHash{"$Part"} = $Part;
-			$TempHash{$PartNo}=$Part;
-			$TempHash{"$Part.Code"} = 'U';  
-			$PartNo++;
-		    }
-		}
-            } split(/\,/,&Apache::lonnet::metadata($meta,'keys'));
-
-            my $Prob = $Map.'___'.$2.'___'.
-                       &Apache::lonnet::declutter( $hash{'src_'.$ResId} );
-            $Code='U';
-            $Tries = 0;
-	    $ParCr = 0;
-            $Wrongs = 0;
-  	    $LatestVersion = $result{"version:$Prob"};       
-
-	    if ( $LatestVersion ) {
-		for ( my $Version=1; $Version<=$LatestVersion; $Version++ ) {
-		    my $vkeys = $result{"$Version:keys:$Prob"};
-		    my @keys = split(/\:/,$vkeys);		
-  
-		    foreach my $Key (@keys) {		  
-			if (($Key=~/\.(\w+)\.solved$/) && ($Key!~/^\d+\:/)) {
-			    my $Part = $1;
-			    $Tries = $result{"$Version:$Prob:resource.$Part.tries"};
-			    $ParCr = $result{"$Version:$Prob:resource.$Part.awarded"};
-			    my $Time = $result{"$Version:$Prob:timestamp"};
-			    $TempHash{"$Part.Time"} = ($Time) ? $Time : 0;
-			    $TempHash{"$Part.Tries"} = ($Tries) ? $Tries : 0;
-			    $TempHash{"$Part.ParCr"} = ($ParCr) ? $ParCr : 0;        
-			    $TotalTries += $TempHash{"$Part.Tries"};
-			    $TotParCr += $TempHash{"$Part.ParCr"};
-#$r->print($Version.'---'.$Prob.'==='.$Time.'<br>');
-			    my $Val = $result{"$Version:$Prob:resource.$Part.solved"};
-			    if ( $Val eq 'correct_by_student' )
-                               { $Wrongs = $Tries - 1; $Code = 'C'; } 
-			    elsif ( $Val eq 'correct_by_override' )
-                               { $Wrongs = $Tries - 1; $Code = 'O'; }                        
-			    elsif ( $Val eq 'incorrect_attempted' || 
-                                $Val eq 'incorrect_by_override' )
-		               { $Wrongs = $Tries; $Code = 'I'; }
-			    $TempHash{"$Part.Code"} = $Code;
-			    $TempHash{"$Part.Wrongs"} = $Wrongs;
-			}
-     		    }
-                } 
-		for ( my $n = 0; $n < $PartNo; $n++ ) {		  
-		    my $part = $TempHash{$n};
-		    my $Yes = 0;
-                    if ( $TempHash{$part.'.Code'} eq 'C' ||
-                         $TempHash{$part.'.Code'} eq 'O'  ) 
-		       {$ProbSolved++;$Yes=1;}		    
-		    my $ptr = "$hash{'title_'.$ResId}";
-		    if ( $PartNo > 1 ) {                
-			$ptr .= " (part $part)";
-			$Dis .= ':';
-		    }
-		    my $Fac = ($TempHash{"$part.Tries"}) ? 
-                              ($TempHash{"$part.ParCr"}/$TempHash{"$part.Tries"}) : 0;
-		    my $DisF;
-		    if ( $Fac > 0 &&  $Fac < 1 ) { 
-			$DisF = sprintf( "%.4f", $Fac );
-		    }
-		    else {$DisF = $Fac;}
-#		    $DisF .= '+'.$TempHash{"$part.Time"};
-		    $TimeTot += $TempHash{"$part.Time"};
-		    $Dis .= $ptr.'*'.$ResId.'='.$DisF.'+'.$Yes;
-		    $ptr .= "*$ResId:$TempHash{$part.'.Tries'}".
-		            ":$TempHash{$part.'.Wrongs'}".
-                            ":$TempHash{$part.'.Code'}";		    
-#$r->print($sname.' -- '.$ptr.'--- timestamp='.$TempHash{"$part.Time"}.'<br>');
-		    push (@list, $ptr);
-		    $TotalOpend++;
-		    $ProbTot++;
-		}
+    my %cache;
+    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
+        return '<html><body>Unable to tie database.</body></html>';
+    }
+
+#    my $Ptr = '';
+#    $Ptr .= '<table border="0"><tbody>';
+#    $Ptr .= '<tr><td align="right"><b>Select Sections</b>';
+#    $Ptr .= '</td>'."\n";
+#    $Ptr .= '<td align="left">'."\n";
+#    my @sectionsSelected = split(':',$cache{'sectionsSelected'});
+#    my @sections = split(':',$cache{'sectionList'});
+#    $Ptr .= &Apache::lonhtmlcommon::MultipleSectionSelect(\@sections,
+#                                                          \@sectionsSelected,
+#                                                          'Statistics');
+#    $Ptr .= '</td></tr></table><br>';
+#    $r->print($Ptr);
+#    $r->rflush();
+#    my %mySections = ();
+#    foreach (@sections) { $mySections{$_} = 'True'; }
+#    $r->print("<br>$cache{'sectionsSelected'}<br>");
+
+    my $Str='';
+    $Str .= '<table border="0"><tr><td bgcolor="#777777">'."\n";
+    $Str .= '<table border="0" cellpadding="3"><tr bgcolor="#e6ffff">'."\n";
+
+    my $displayString = '<td align="left"><a href="/adm/statistics?';
+    $displayString .= 'sort=LINKDATA">DISPLAYDATA&nbsp</a></td>'."\n";
+    $Str .= &Apache::lonhtmlcommon::CreateHeadings(\%cache,
+                                                   $studentInformation,
+                                                   $headings, $displayString);
+    $Str .= '</tr>'."\n";
+
+    my $alternate=0;
+    foreach (@$students) {
+#        if ($mySections{$cache{$_.':'.'section'}} ne 'True') {next;}
+        my ($username, $domain) = split(':', $_);
+        if($alternate) {
+            $Str .= '<tr bgcolor="#ffffe6">';
+        } else {
+            $Str .= '<tr bgcolor="#ffffc6">';
+        }
+        $alternate = ($alternate + 1) % 2;
+        foreach my $data (@$studentInformation) {
+            $Str .= '<td>';
+            if($data eq 'fullname') {
+                $Str .= '<a href="/adm/statistics?reportSelected=';
+                $Str .= &Apache::lonnet::escape('Student Assessment');
+                $Str .= '&StudentAssessmentStudent=';
+                $Str .= &Apache::lonnet::escape($cache{$_.':'.$data}).'">';
+                $Str .= $cache{$_.':'.$data}.'&nbsp';
+                $Str .= '</a>';
+            } elsif($data eq 'updateTime') {
+                $Str .= '<a href="/adm/statistics?reportSelected=';
+                $Str .= &Apache::lonnet::escape('Class list');
+                $Str .= '&download='.$_.'">';
+                $Str .= $cache{$_.':'.$data}.'&nbsp';
+                $Str .= '&nbsp</a>';
+            } else {
+                $Str .= $cache{$_.':'.$data}.'&nbsp';
             }
-	    else { 
-		for(my $n=0; $n<$PartNo; $n++) {
-		    push (@list, "$hash{'title_'.$ResId}*$ResId:0:0:U");
-		    $ProbTot++; 
-		}
-	    }
-        }
-	if ( $TotalTries ) {
-	    my $DisFac = ( $TotalTries ) ? ($TotParCr/$TotalTries) : 0;
-#	    my $DisFactor = int(sprintf( "%.4f", $DisFac ) * 100);
-	    my $DisFactor = sprintf( "%.4f", $DisFac );
-	    my $time;
-	    if ($ProbSolved){
-		$time = int(($TimeTot/$ProbSolved)/10000000);
-	    }
-	    $DiscFac{($DisFactor.':'.$sname.':'.$ProbTot.':'.$TotalOpend.':'.
-                      $TotalTries.':'.$ProbSolved.':'.$time)}=$Dis;
-#$r->print($DisFactor.$sname.'<br> --- Dis= '.$Dis.'<br>');
-	}
-    }
-    #$r->print($sname.' PrCr= '.$TotParCr.' Slvd= '.$ProbSolved.' Tries='.$TotalTries.'<br>');
-}
-
-
-# ------------------------------------------------------------ Build page table
-sub tracetable {
-    my ($rid,$beenhere)=@_;
-    $rid=~/(\d+)\.(\d+)/;
-    $maps{&Apache::lonnet::declutter($hash{'map_id_'.$1})}='';#$hash{'title_'.$rid}; 
-    unless ($beenhere=~/\&$rid\&/) {
-       $beenhere.=$rid.'&'; 
-       if (defined($hash{'is_map_'.$rid})) {
-	   my $cmap=$hash{'map_type_'.$hash{'map_pc_'.$hash{'src_'.$rid}}};
-           if ( $cmap eq 'sequence' || $cmap eq 'page' ) { 
-               $cols[$#cols+1]=0;
-	       $HWN++;
-               $mapsort[$HWN]=$rid.$hash{'title_'.$rid}; 
-               #$maps{&Apache::lonnet::declutter($hash{'src_'.$rid})}= 
-               #      $hash{'title_'.$rid}; 
-           }
-           if ((defined($hash{'map_start_'.$hash{'src_'.$rid}})) &&
-               (defined($hash{'map_finish_'.$hash{'src_'.$rid}}))) {
-              my $frid=$hash{'map_finish_'.$hash{'src_'.$rid}};
-
-                &tracetable($hash{'map_start_'.$hash{'src_'.$rid}},
-                '&'.$frid.'&');
-
-              if ($hash{'src_'.$frid}) {
-                 if ($hash{'src_'.$frid}=~
-                                 /\.(problem|exam|quiz|assess|survey|form)$/) {
-		     $cols[$#cols+1]=$frid;
-		     $mapsort[$HWN] .= '&'.$frid;
-                 }
-	      }
-	   }
-       } else {
-          if ($hash{'src_'.$rid}) {
-             if ($hash{'src_'.$rid}=~
-                                 /\.(problem|exam|quiz|assess|survey|form)$/) {
-	         $cols[$#cols+1]=$rid;
-		 $mapsort[$HWN] .= '&'.$rid;
-             }
-          }
-       }
-       if (defined($hash{'to_'.$rid})) {
-          map {
-              &tracetable($hash{'goesto_'.$_},$beenhere);
-          } split(/\,/,$hash{'to_'.$rid});
-       }
-    }
-}
-
-sub MySort {          
-    if ( $Pos > 0 && $Pos < 11 ) {
-	if ($ENV{'form.order'} eq 'Descending') {$b <=> $a;}
-	else { $a <=> $b; }
-    }
-    else {
-	if ($ENV{'form.order'} eq 'Descending') {$b cmp $a;}
-	else { $a cmp $b; }
-    }
-}
-
-sub Build_Statistics {
-    $r->print(<<ENDPOP);
-<script>
-    popwin=open('','popwin','width=400,height=100');
-    popwin.document.writeln('<html><body bgcolor="#8cee8c">'+
-      '<title>LON-CAPA Statistics</title>'+
-      '<h4>Computation Progress</h4>'+
-      '<form name=popremain>'+
-      '<input type=text size=35 name=remaining value=Starting></form>'+
-      '</body></html>');
-    popwin.document.close();
-</script>
-ENDPOP
 
+            $Str .= '</td>'."\n";
+        }
+    }
+
+    $Str .= '</tr>'."\n";
+    $Str .= '</table></td></tr></table>'."\n";
+    $r->print($Str);
     $r->rflush();
-# ---------------------------- Gathering the Data of students' tries
-    my $index;
-    for ($index=0;$index<=$#students;$index++) {
-#----------- update progress
-        $r->print('<script>popwin.document.popremain.remaining.value="'.
-                  'Computing '.($index+1).'/'.($#students+1).': '.
-                  $students[$index].'";</script>');
-        $r->rflush();
 
-        &ExtractStudentData($students[$index],$cid);
+    untie(%cache);
+
+    return;
+}
+
+sub CreateMainMenu {
+    my ($status, $reports)=@_;
+
+    my $Str = '';
+
+    $Str .= '<table border="0"><tbody><tr>'."\n";
+    $Str .= '<td></td><td></td>'."\n";
+    $Str .= '<td align="center"><b>Select a Report</b></td>'."\n";
+    $Str .= '<td align="center"><b>Student Status</b></td></tr>'."\n";
+    $Str .= '<tr>'."\n";
+    $Str .= '<td align="center"><input type="submit" name="Refresh" ';
+    $Str .= 'value="Refresh" /></td>'."\n";
+    $Str .= '<td align="center"><input type="submit" name="DownloadAll" ';
+    $Str .= 'value="Update All Student Data" /></td>'."\n";
+    $Str .= '<td align="center">';
+    $Str .= '<select name="reportSelected" onchange="document.';
+    $Str .= 'Statistics.submit()">'."\n";
+
+    foreach (sort(keys(%$reports))) {
+        next if($_ eq 'reportSelected');
+        $Str .= '<option name="'.$_.'"';
+        if($reports->{'reportSelected'} eq $reports->{$_}) {
+            $Str .= ' selected=""';
+        }
+        $Str .= '>'.$reports->{$_}.'</option>'."\n";
     }
-#--------------------- close Progress Line
-    $r->print('<script>popwin.close()</script>');
-    $r->rflush(); 
-# -------------------- sorting the Data
-    @list = sort(@list);
-    $OpSel2='';
-    $OpSel1='selected';
- 		   
-    $p_count = 0; 
-    my $nIdx = 0;
-    my $dummy; 
-    my $p_val;
-    my $ResId;
-    my $NoElements = $#list + 1;
-#-------------------------------- loop for data representation
-    while ( $nIdx < $NoElements ) {
-        my %storestats=();
-	my ($Prob,$Tries,$Wrongs,$Code)=split(/\:/,$list[$nIdx]);
-	my $Temp = $Prob;
-	my $MxTries = 0;
-	my $TotalTries = 0;
-	my $YES = 0;
-	my $Incorrect = 0;
-	my $Override = 0;
-	my $StdNo = 0;
-	my @StdLst; 
-	do {
-	    $nIdx++;
-	    $StdNo++;
-	    $StdLst[ $StdNo ] = $Tries;
-	    $TotalTries += $Tries;
-	    if ( $MxTries < $Tries ) { $MxTries = $Tries; } 
-	    if ( $Code eq 'C' ){ $YES++; }
-	    elsif( $Code eq 'I' ) { $Incorrect++; }
-	    elsif( $Code eq 'O' ) { $Override++; }
-	    elsif( $Code eq 'U' ) { $StdNo--; }
-	    ($Prob,$Tries,$Wrongs,$Code)=split(/\:/,$list[$nIdx]);
-	} while ( $Prob eq $Temp && $nIdx < $NoElements );	
-
-	$p_count++;
-
-	($Temp,$ResId)=split(/\*/,$Temp);
-
-        $Temp = '<a href="'.$hash{'src_'.$ResId}.'" target="_blank">'.$Temp.'</a>';
-    
-	my $res = &Apache::lonnet::declutter($hash{'src_'.$ResId});
-        my $urlres=$res;
-
-        $ResId=~/(\d+)\.(\d+)/;
-        my $Map = &Apache::lonnet::declutter( $hash{'map_id_'.$1} );
-        $urlres=$Map;
- 
-
-        $res = '<a href="'.$hash{'src_'.$ResId}.'">'.$res.'</a>';
-
-        #$Map = '<a href="'.$Map.'">'.$res.'</a>';
-
-#------------------------ Compute the Average of Tries about one problem
-	my $Average = ($StdNo) ? $TotalTries/$StdNo : 0;
-
-        $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___timestamp'}=time;       
-        $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___stdno'}=$StdNo;
-        $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___avetries'}=$Average;
-   
-#-------------------------------- Compute percentage of Wrong tries
-	my $Wrong = ( $StdNo ) ? 100 * ( $Incorrect / $StdNo ) : 0;
-
-#-------------------------------- Compute Standard Deviation
-	my $StdDev = 0; 
-	if ( $StdNo > 1 ) {
-	    for ( my $n = 0; $n < $StdNo; $n++ ) {
-                my $Dif = $StdLst[ $n ]-$Average;
-		$StdDev += $Dif*$Dif;
-	    } 
-	    $StdDev /= ( $StdNo - 1 );
-	    $StdDev = sqrt( $StdDev );
-	}
-
-#-------------------------------- Compute Degree of Difficulty
-	my $DoDiff = 0;
-	if( $TotalTries > 0 ) {
-	    $DoDiff = 1 - ( ( $YES + $Override ) / $TotalTries );
-#	    $DoDiff =  ($TotalTries)/($YES + $Override+ 0.1);	    
-	}
-       
-        $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___difficulty'}=$DoDiff;
-
-#-------------------------------- Compute the Skewness
-	my $Skewness = 0;
-        my $Sum = 0; 
-	if ( $StdNo > 0 && $StdDev > 0 ) {
-	    for ( my $n = 0; $n < $StdNo; $n++ ) {
-                my $Dif = $StdLst[ $n ]-$Average;
-		$Skewness += $Dif*$Dif*$Dif;
-	    } 
-	    $Skewness /= $StdNo;
-	    $Skewness /= $StdDev*$StdDev*$StdDev;
-	}
-#-----------------  Some restition in presenting the float numbers
-	my $Avg = sprintf( "%.2f", $Average );
-	my $Wrng = sprintf( "%.1f", $Wrong );
-	my $SD = sprintf( "%.1f", $StdDev );
-	my $DoD = sprintf( "%.2f", $DoDiff );
-	my $Sk = sprintf( "%.1f", $Skewness );
-    
-	$CachData{($p_count-1)}=$Temp.':'.$StdNo.':'.$TotalTries.':'.
-                                $MxTries.':'.$Avg.':'.$YES.':'.
-                                $Override.':'.$Wrng.':'.$SD.':'.
-                                $Sk.':'.$DoD.':'.$Map.':'.$Prob;
-
-        $urlres=~/^(\w+)\/(\w+)/;
-        if ($StdNo) { 
-           &Apache::lonnet::put('resevaldata',\%storestats,$1,$2); 
-        }
-
-#-------------------------------- Row of statistical table
-        if ( $DiscFlag == 0 ) {
-	    $r->print( "\n".'<tr>'.
-               "\n".'<td>'.$p_count.'</td>'.
-               "\n".'<td>'.$Temp.'</td>'.
-               "\n".'<td>'.$StdNo.'</td>'.
-               "\n".'<td>'.$TotalTries.'</td>'.
-               "\n".'<td>'.$MxTries.'</td>'.
-               "\n".'<td>'.$Avg.'</td>'.
-               "\n".'<td>'.$YES.'</td>'.
-               "\n".'<td>'.$Override.'</td>'.
-               "\n".'<td>'.$Wrng.'</td>'.
-               "\n".'<td>'.$SD.'</td>'.
-               "\n".'<td>'.$Sk.'</td>'.
-               "\n".'<td>'.$DoD.'</td>'.
-               "\n".'<td>'.$Map.'</td>'.
-                       "\n".'</tr>' );
-	    $GraphDat{$nIdx}=$DoD.':'.$Wrng;
-	} 
-    }
-}
-
-
-sub Cache_Statistics {
-    my @list = ();
-    my $Useful;
-    my $UnUseful;
-    my %myHeader = reverse( %Header );
-    $Pos = $myHeader{$ENV{'form.sort'}};
-    $p_count = 0;
-
-    foreach my $key( keys %CachData) { 
-	my @Temp=split(/\:/,$CachData{$key});
-	if ( $Pos == 0 || $Pos == 11 ) {
-	    ($UnUseful,$Useful)=split(/\>/,$Temp[$Pos]);
-	}
-	else {
-	    $Useful = $Temp[$Pos];
-	}   
-	$list[$p_count]=$Useful.'&'.$CachData{$key};
-        $p_count++;
-    }
-
-    @list = sort MySort (@list);
-
-    for ( my $nIdx = 0; $nIdx < $p_count; $nIdx++ ) {
-	my( $Pre, $Post ) = split(/\&/,$list[$nIdx]); 
-	my ($Temp,$StdNo,$TotalTries,$MxTries,$Avg,$YES,
-            $Override,$Wrng,$SD,$Sk,$DoD,$res,$Prob)=split(/\:/,$Post);	
-	$r->print( "\n".'<tr>'.
-               "\n".'<td>'.($nIdx+1).'</td>'.
-               "\n".'<td  bgcolor="#FFFFFF">'.$Temp.'</td>'.
-               "\n".'<td>'.$StdNo.'</td>'.
-               "\n".'<td>'.$TotalTries.'</td>'.
-               "\n".'<td>'.$MxTries.'</td>'.
-               "\n".'<td>'.$Avg.'</td>'.
-               "\n".'<td>'.$YES.'</td>'.
-               "\n".'<td>'.$Override.'</td>'.
-               "\n".'<td>'.$Wrng.'</td>'.
-               "\n".'<td>'.$SD.'</td>'.
-               "\n".'<td>'.$Sk.'</td>'.
-               "\n".'<td>'.$DoD.'</td>'.
-               "\n".'<td>'.$res.'</td>'.
-               "\n".'</tr>' );
-	$GraphDat{$nIdx}=$DoD.':'.$Wrng;
-    } 
-}
-
-# ------------------------------------------- Prepare data for Graphical chart
-
-sub GetGraphData {
-    my $Tag = shift;
-    my $Col;
-    my $data='';
-    my $count = 0;
-    my $Max = 0;
-    my $cid=$ENV{'request.course.id'};
-    my $GraphDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
-                  "_$ENV{'user.domain'}_$cid\_graph.db";
-    foreach (keys %GraphDat) {delete $GraphDat{$_};}
-    if (-e "$GraphDB") {
-	if (tie(%GraphDat,'GDBM_File',"$GraphDB",&GDBM_READER,0640)) {
-	    if ( $Tag eq 'DoDiff Graph' ) {
-		$Tag = 'Degree-of-Difficulty';
-		$Col = 0;
-	    }
-	    else {
-		$Tag = 'Wrong-Percentage';
-		$Col = 1;
-	    }
-	    foreach (sort NumericSort keys %GraphDat) { 
-		my @Temp=split(/\:/,$GraphDat{$_});
-                my $inf = $Temp[$Col]; 
-		if ( $Max < $inf ) {$Max = $inf;}
-		$data .= $inf.',';
-		$count++;
-	    }
-            untie(%GraphDat);
-	    my $Course = $ENV{'course.'.$cid.'.description'};
-	    $Course =~ s/\ /"_"/eg;
-	    $GData=$Course.'&'.$Tag.'&'.$Max.'&'.$count.'&'.$data;
-
-	}
-	else {
-	    $r->print("Unable to tie hash to db file");
-	}
-    }
-}
-
-
-sub initial {
-# --------------------------------- Initialize the global varaibles
-  undef @students;
-  undef @cols;
-  undef %maps;
-  undef %section;
-  undef %StuBox;
-  undef @list;
-  undef %CachData;
-  undef %GraphDat;
-  undef %DiscFac;
-  undef $CurMap;
-  undef $CurSec;
-  undef $CurStu;
-  undef $p_count;
-  undef $Pos;
-  undef $GData;
-}
-
-
-sub ClassList {
-
-    &GetStatus();
-
-    $cid=$ENV{'request.course.id'};
-    my $chome=$ENV{'course.'.$cid.'.home'};
-    my ($cdom,$cnum)=split(/\_/,$cid);
-# ----------------------- Get first and last resource, see if there is anything
-    $firstres=$hash{'map_start_/res/'.$ENV{'request.course.uri'}};
-    $lastres=$hash{'map_finish_/res/'.$ENV{'request.course.uri'}};
-    if (($firstres) && ($lastres)) {
-# ----------------------------------------------------------------- Render page
-	my $classlst=&Apache::lonnet::reply
-                 ('dump:'.$cdom.':'.$cnum.':classlist',$chome);
-	my $StudNo = 0;
-	unless ($classlst=~/^error\:/) {
-	    foreach (sort split(/\&/,$classlst)) {
-		my ($name,$value)=split(/\=/,$_);
-		my ($end,$start)=split(/\:/,&Apache::lonnet::unescape($value));
-		$name=&Apache::lonnet::unescape($name);
-		my ($sname,$sdom)=split(/\:/,$name);
-		my $ssec=&Apache::lonnet::usection($sdom,$sname,$cid);
-                if ($ssec==-1) {next;}
-		$ssec=($ssec) ? $ssec : '(none)';
-		$ssec=(int($ssec)) ? int($ssec) : $ssec;
-		#$r->print($sname.'...'.$ssec.'<br>');
-		$section{$ssec}=$ssec;
-		if ($CurSec eq 'All Sections' || $ssec eq $CurSec) {
-		    $students[$StudNo]=$name;
-		    $StuBox{$sname}=$ssec;
-		}
-		$StudNo++;
-	    }
-	}
-	else {
-	    $r->print('<h1>Could not access course data</h1>');
-	} 
-        $r->print("Total number of students : ".($#students+1));
-        $r->rflush();
-# --------------- Find all assessments and put them into some linear-like order
-	&tracetable($firstres,'&'.$lastres.'&');
+    $Str .= '</select></td>'."\n";
 
-#my $c=0;
-#foreach(@mapsort) {
-#    $c++;
-#    $r->print('<br>'.$mapsort[$c]);
-#}
-#$r->print('<br> Count = '.$c);
-
-    }
-
-# ------------------------------------------------------------- End render page 
-    else {
-	$r->print('<h3>Undefined course sequence</h3>');
-    }
-    &MapSecOptions();
-}
-
-
-sub Menu {
-    my $InpStr = $ENV{'form.sort'};
-    if ( $InpStr eq 'DoDiff Graph' || $InpStr eq '%Wrong Graph' ) {      
-	&GetGraphData($InpStr);
-    	$r->print('<IMG src="/cgi-bin/graph.gif?'.$GData.'" />');
-    }
-    else {
-	$r->print('<html><head><title>LON-CAPA Statistics</title></head>');
-
-
-        $r->print('<body bgcolor="#FFFFFF">'.
-                  '<script>window.focus(); window.width=500;window.height=500; </script>'.
-                  '<img align=right src=/adm/lonIcons/lonlogos.gif>');
-# ---------------------------------------------------------------- Course title
-        $r->print('<h1> Course : "'.
-                  $ENV{'course.'.$ENV{'request.course.id'}.
-                  '.description'}.'"</h1><h2>'.localtime().'</h2>');
-# ------------------------------- This is going to take a while, produce output
-        $r->rflush();	
-
-	$r->print("\n".'<form name=stat method=post action="/adm/statistics" >');
-
-	my $content = $ENV{'form.sort'};
-	if ($content eq '' || $content eq 'Return to Menu') {
-	    my $Ptr = '<h3>';
-	    $Ptr .= '<input type=submit name=sort value="Problem Evaluation"/>';#General Statistics"/>';
-	    $Ptr .= '<br><br>';
-	    $Ptr .= '<input type=submit name=sort value="Student Assessment"/>';
-	    $Ptr .= '<br><br>';
-#	    $Ptr .= '<input type=submit name=sort value=Discrimination>';#"Problem Evaluation"/>';
-	    $Ptr .= '</h3>';
-	    $r->print( $Ptr );
-      	}
-	else {
-	    &initial();
-	    &ClassList();
-	    if ( $content eq 'Discrimination' || #'Problem Evaluation' ||
-                 $content eq 'Recalculate Discrimintion Factor' ) {
-		&CreateDiscFac();
-	    }
-	    elsif ( $content eq 'Student Assessment' || 
-                    $content eq 'Create Student Report' ) {
-		&StudentOptions();
-		&StudentReport($CurStu,$StuBox{"$CurStu"});
-	    }
-	    else {
-		&PreStatTable();
-	    }
-	}
-	$r->print("\n".'</form>'.
-                  "\n".'</body>'.
-                  "\n".'</html>');
-	$r->rflush();
-    }
-}
-
-sub StudentOptions {
-    my $OpSel5='';
-    $CurStu = $ENV{'form.student'};
-    if ( $CurStu eq '' ) { 
-        $CurStu = 'All Students';
-        $OpSel5 = 'selected';
-    }
-    my $Ptr ='';
-# ----------------------------------- Loading the Students Combobox
-    $Ptr .= '<br><b>Select Student</b>'."\n".
-       	    '<select name="student">'."\n". 
-	    '<option '.$OpSel5.'>All Students</option>';                     	     	     
-    foreach my $key ( sort keys %StuBox ) {	          
-	$Ptr .= '<option';
-	if ($CurStu eq $key) {$Ptr .= ' selected';}     
-        $Ptr .= '>'.$key."</option>\n";	     
-    }
-    $Ptr .= '</select>';
-    $Ptr .= '<br><input type="submit" name="sort" value="Create Student Report" />';
-    $r->print( $Ptr );
-    $r->rflush();	
-}
-
-sub GetStatus {
-
-    $OpSelDis1='';
-    $OpSelDis2='';
-    $OpSel1='';
-    $OpSel2='';
-    $OpSel3='';
-    $OpSel4='';
-
-#    if ( $ENV{'form.DisType'} eq 'Total Number of Correct Answers' ) { 
-#	$OpSelDis1='selected'; 
-#	$CurDis=0;
-#    }
-#    else { $OpSel2 = 'selected'; $CurDis = 1;}
-
-    if ( $ENV{'form.order'} eq 'Descending' ) { $OpSel2='selected'; }
-    else { $OpSel1 = 'selected'; }
-    $CurMap = $ENV{'form.maps'};
-    if ( $CurMap eq '' ) { 
-	$CurMap = 'All Maps';
-	$OpSel3 = 'selected';
-    }
-    $CurSec = $ENV{'form.section'};
-    if ( $CurSec eq '' ) { 
-	$CurSec = 'All Sections';
-        $OpSel4 = 'selected';
-    }
-}
-
-
-sub MapSecOptions {
-# ----------------------------------- Loading the Maps Combobox
-    my $Ptr = '<br>';
-    $Ptr .= '<br><input type="submit" name="sort" value="Return to Menu" />';
-    $Ptr .= '<br><b> Select &nbsp; Map &nbsp; &nbsp; </b>'."\n".
-       	    '<select name="maps">'."\n". 
-	    '<option '.$OpSel3.'>All Maps</option>';                     	     	     
-    foreach my $key ( sort keys %maps ) {	          
-	$Ptr .= '<option';
-        if ($CurMap eq $key) {$Ptr .= ' selected';}	     
-	$Ptr .= '>'.$key."</option>\n";	     
-    }
-    $Ptr .= '</select>';
-    $Ptr .= '&nbsp;&nbsp;&nbsp;';
-
-# ----------------------------------- Loading the Sections Combobox
-    $Ptr .= '<br><b>Select Section</b>'."\n".
-       	    '<select name="section">'."\n". 
-	    '<option '.$OpSel4.'>All Sections</option>';                     	     	     
-    foreach my $key ( sort keys %section ) {	          
-	$Ptr .= '<option';
-        if ($CurSec eq $key) {$Ptr .= ' selected';}     
-	$Ptr .= '>'.$key."</option>"."\n";	     
+    $Str .= '<td align="center">';
+    $Str .= &Apache::lonhtmlcommon::StatusOptions($status, 'Statistics');
+    $Str .= '</td>'."\n";
+
+    $Str .= '</tr></tbody></table>'."\n";
+    $Str .= '<hr>'."\n";
+
+    return $Str;
+}
+
+sub BuildStatistics {
+    my ($r)=@_;
+
+    my $c = $r->connection;
+    my @studentInformation=('fullname','section','id','domain','username',
+                            'updateTime');
+    my @headings=('Full Name', 'Section', 'PID', 'Domain', 'User Name',
+                  'Last Updated');
+    my $spacing = '   ';
+
+    my %reports = ('classlist'          => 'Class list',
+                   'problem_statistics' => 'Problem Statistics',
+                   'student_assessment' => 'Student Assessment',
+		   'percentage'         => 'Correct-problems Plot',
+#                   'activitylog'        => 'Activity Log',
+                   'reportSelected'     => 'Class list');
+
+    my %cache;
+    my $courseID=$ENV{'request.course.id'};
+    my $cacheDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
+                  "_$ENV{'user.domain'}_$courseID\_statistics.db";
+
+    $r->print(&Apache::lonhtmlcommon::Title('Course Statistics and Charts'));
+
+    my ($returnValue, $students) = &PrepareData($c, $cacheDB,
+                                                \@studentInformation,
+                                                \@headings,$r);
+    if($returnValue ne 'OK') {
+        $r->print($returnValue."\n".'</body></html>');
+        return OK;
+    }
+    if(!$c->aborted()) {
+        &Apache::loncoursedata::CheckForResidualDownload($cacheDB,
+                                                         'true', 'true',
+                                                         $courseID,
+                                                         $r, $c);
+    }
+
+    my $GoToPage;
+    if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
+        $GoToPage = $cache{'reportSelected'};
+        $reports{'reportSelected'} = $cache{'reportSelected'};
+        if(defined($cache{'reportKey'}) &&
+           !exists($reports{$cache{'reportKey'}}) &&
+           $cache{'reportKey'} ne 'false') {
+            $reports{$cache{'reportKey'}} = $cache{'reportSelected'};
+        }
+
+        if(defined($cache{'OptionResponses'})) {
+            $reports{'problem_analysis'} = 'Option Response Analysis';
+        }
+
+        $r->print('<form name="Statistics" ');
+        $r->print('method="post" action="/adm/statistics">');
+        $r->print(&CreateMainMenu($cache{'Status'}, \%reports));
+        $r->rflush();
+        untie(%cache);
+    } else {
+        $r->print('<html><body>Unable to tie database.</body></html>');
+        return OK;
+    }
+
+    if($GoToPage eq 'Activity Log') {
+        &Apache::lonproblemstatistics::Activity();
+    } elsif($GoToPage eq 'Problem Statistics') {
+        &Apache::lonproblemstatistics::BuildProblemStatisticsPage($cacheDB,
+                                                                  $students,
+                                                                  $courseID,
+                                                                  $c,$r);
+    } elsif($GoToPage eq 'Option Response Analysis') {
+        &Apache::lonproblemanalysis::BuildProblemAnalysisPage($cacheDB, $r);
+    } elsif($GoToPage eq 'Student Assessment') {
+        &Apache::lonstudentassessment::BuildStudentAssessmentPage($cacheDB,
+                                                          $students,
+                                                          $courseID,
+                                                          'Statistics',
+                                                          \@headings,
+                                                          $spacing,
+                                                          \@studentInformation,
+                                                          $r, $c);
+    } elsif($GoToPage eq 'Analyze') {
+        &Apache::lonproblemanalysis::BuildAnalyzePage($cacheDB, $students,
+                                                      $courseID, $r);
+    } elsif($GoToPage eq 'DoDiffGraph' || $GoToPage eq 'PercentWrongGraph') {
+        my $courseDescription = $ENV{'course.'.$courseID.'.description'};
+        $courseDescription =~ s/\ /"_"/eg;
+        &Apache::lonproblemstatistics::BuildGraphicChart($GoToPage, $cacheDB,
+                                                         $courseDescription,
+                                                         $students, $courseID,
+                                                         $r, $c);
+    } elsif($GoToPage eq 'Class list') {
+        &DisplayClasslist($r);
+#        &BuildClasslist($cacheDB, $students, \@studentInformation,
+#                        \@headings, $r);
+    } elsif($GoToPage eq 'Correct-problems Plot') {
+	&Apache::lonpercentage::BuildPercentageGraph($cacheDB, $students,
+						     $courseID, $c, $r);
     }
-    $Ptr .= '</select>'."\n";
 
-    $r->print( $Ptr );
+    $r->print('</form>'."\n");
+    $r->print("\n".'</body>'."\n".'</html>');
     $r->rflush();
-}
 
+    return OK;
+}
 
 # ================================================================ Main Handler
 
 sub handler {
-    $r=shift;
+    my $r=shift;
 
-    if (&Apache::lonnet::allowed('vgr',$ENV{'request.course.id'})) {
-# ------------------------------------------- Set document type for header only
-	if ($r->header_only) {
-	    if ($ENV{'browser.mathml'}) {
-		$r->content_type('text/xml');
-	    } 
-	    else {
-		$r->content_type('text/html');
-	    }
-	    $r->send_http_header;
-	    return OK;
-	}    
-	my $requrl=$r->uri;
-# ----------------------------------------------------------------- Tie db file
+#    $jr = $r;
 
-	undef %hash;
+    my $loaderror=&Apache::lonnet::overloaderror($r);
+    if ($loaderror) { return $loaderror; }
+    $loaderror=
+       &Apache::lonnet::overloaderror($r,
+         $ENV{'course.'.$ENV{'request.course.id'}.'.home'});
+    if ($loaderror) { return $loaderror; }
 
-	if ($ENV{'request.course.fn'}) {
-	    my $fn=$ENV{'request.course.fn'};
-	    if (-e "$fn.db") {
-		if (tie(%hash,'GDBM_File',"$fn.db",&GDBM_READER,0640)) {
-# ------------------------------------------------------------------- Hash tied
-		    $r->content_type('text/html');
-		    $r->send_http_header;
-		    &Menu();
-		}
-		else {
-		    $r->content_type('text/html');
-		    $r->send_http_header;
-		    $r->print('<html><body>Coursemap undefined.</body></html>');
-		}
-# ------------------------------------------------------------------ Untie hash
-		unless (untie(%hash)) {
-		    &Apache::lonnet::logthis("<font color=blue>WARNING: ".
-                            "Could not untie coursemap $fn (browse).</font>"); 
-		}
-
-# -------------------------------------------------------------------- All done
-		return OK;
-# ----------------------------------------------- Errors, hash could no be tied
-	    }
-	} 
-	else {
-	    $ENV{'user.error.msg'}="$requrl:bre:0:0:Course not initialized";
-	    return HTTP_NOT_ACCEPTABLE; 
-	}
-    }
-    else {
+    unless(&Apache::lonnet::allowed('vgr',$ENV{'request.course.id'})) {
         $ENV{'user.error.msg'}=
         $r->uri.":vgr:0:0:Cannot view grades for complete course";
+        return HTTP_NOT_ACCEPTABLE;
+    }
 
-        return HTTP_NOT_ACCEPTABLE; 
+    # Set document type for header only
+    if($r->header_only) {
+        if ($ENV{'browser.mathml'}) {
+            $r->content_type('text/xml');
+        } else {
+            $r->content_type('text/html');
+        }
+        &Apache::loncommon::no_cache($r);
+        $r->send_http_header;
+        return OK;
     }
+
+    unless($ENV{'request.course.fn'}) {
+	my $requrl=$r->uri;
+        $ENV{'user.error.msg'}="$requrl:bre:0:0:Course not initialized";
+        return HTTP_NOT_ACCEPTABLE;
+    }
+
+    $r->content_type('text/html');
+    $r->send_http_header;
+
+    &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},
+                                            ['sort',
+                                             'StudentAssessmentStudent']);
+
+    &PrepareClasslist($r);
+
+    &PrepareCourseData($r);
+
+    &BuildStatistics($r);
+
+    return OK;
 }
 1;
-__END__
 
+=pod
+
+=back
 
+=cut
+
+__END__