--- loncom/interface/statistics/lonproblemstatistics.pm	2002/07/25 19:29:23	1.2
+++ loncom/interface/statistics/lonproblemstatistics.pm	2004/03/26 22:04:22	1.73
@@ -1,7 +1,6 @@
 # The LearningOnline Network with CAPA
-# (Publication Handler
 #
-# $Id: lonproblemstatistics.pm,v 1.2 2002/07/25 19:29:23 minaeibi Exp $
+# $Id: lonproblemstatistics.pm,v 1.73 2004/03/26 22:04:22 matthew Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -26,1037 +25,1146 @@
 # http://www.lon-capa.org/
 #
 # (Navigate problems for statistical reports
-# YEAR=2001
-# 5/5,7/9,7/25/1,8/11,9/13,9/26,10/5,10/9,10/22,10/26 Behrouz Minaei
-# 11/1,11/4,11/16,12/14,12/16,12/18,12/20,12/31 Behrouz Minaei
-# YEAR=2002
-# 1/22,2/1,2/6,2/25,3/2,3/6,3/17,3/21,3/22,3/26,4/7,5/6 Behrouz Minaei
-# 5/12,5/14,5/15,5/19,5/26,7/16,7/25  Behrouz Minaei
 #
-###
+###############################################
+###############################################
 
-package Apache::lonproblemstatistics; 
-
-use strict;
-use Apache::lonnet();
-use Apache::lonhtmlcommon;
-use Apache::loncoursedata;
-use GDBM_File;
+=pod
 
-my %mapsort;
+=head1 NAME
 
-sub BuildProblemStatisticsPage {
-    my ($cacheDB, $students, $courseID, $c, $r,%color)=@_;
-    my %cache;
-    #my %DoDiff;
-    unless(tie(%cache,'GDBM_File',$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 Map</b></td>'."\n";
-    $Ptr .= '<td align="left">';
-    $Ptr .= &Apache::lonhtmlcommon::MapOptions(\%cache, 'ProblemStatistics');
-    $Ptr .= '</td></tr>'."\n";
-    $Ptr .= &AscendOrderOptions($cache{'Ascend'});
-    $Ptr .= &ProblemStatisticsButtons($cache{'DisplayFormat'});
-    $Ptr .= '</table>';
-
-    $Ptr .= &ProblemStatisticsLegend();
-
-    untie(%cache);
-    foreach (@$students) {
-        my $courseData = 
-            &Apache::loncoursedata::DownloadCourseInformation($_, $courseID);
-        last if ($c->aborted());
-        if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT,0640)) {
-            &Apache::loncoursedata::ProcessStudentData(\%cache, 
-                                                       $courseData, $_);
-            untie(%cache);
-        }
-    }
-    if($c->aborted()) { return $Ptr; }
-
-    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
-        return '<html><body>Unable to tie database.</body></html>';
-    }
-    my $discriminantFactor;
-    my @list=();
-    my %Discuss=&Apache::loncoursedata::LoadDiscussion($courseID);
-    my $index=0;
-    foreach (@$students) {
-	#&Apache::lonstatistics::Update_PrgWin(++$index,$r);
-        $discriminantFactor = &ExtractStudentData(\%cache, $_, \@list,\%Discuss);
-    }
-    #&Apache::lonstatistics::Close_PrgWin($r);
-
-    return $Ptr;
-    my ($upper, $lower) = &Discriminant($discriminantFactor);
-    my %Header = (0,"Homework Sets Order",1,"#Stdnts",2,"Tries",3,"Mod",
-                  4,"Mean",5,"#YES",6,"#yes",7,"%Wrng",8,"DoDiff",
-                  9,"S.D.",10,"Skew.",11,"D.F.1st",12,"D.F.2nd", 13, "Disc.");
-
-    my %GraphDat= &BuildStatisticsTable(\%cache, $discriminantFactor, \@list, 
-                                        \%Header, $students, $r, \%color);
+lonproblemstatistics
 
-    untie(%cache);
+=head1 SYNOPSIS
 
-    return $Ptr;
-}
+Routines to present problem statistics to instructors via tables,
+Excel files, and plots.
 
-sub BuildDiffGraph {
-    my ($r)=@_;
+=over 4
 
-    my $graphData = &GetGraphData('DiffGraph', $r);
-    return '<IMG src="/cgi-bin/graph.gif?'.$graphData.'" />';
-}
+=cut
 
-sub BuildWrongGraph {
-    my ($r)=@_;
+###############################################
+###############################################
 
-    my $graphData = &GetGraphData('WrongGraph', $r);
-    return '<IMG src="/cgi-bin/graph.gif?'.$graphData.'" />';
-}
+package Apache::lonproblemstatistics;
 
-#---- Activity log -------------------------------------------------------
+use strict;
+use Apache::lonnet();
+use Apache::loncommon();
+use Apache::lonhtmlcommon;
+use Apache::loncoursedata;
+use Apache::lonstatistics;
+use Apache::lonlocal;
+use Spreadsheet::WriteExcel;
+use Apache::lonstathelpers();
+use Time::HiRes;
+
+my @StatsArray;
+
+##
+## Localization notes:
+##
+## in @Fields[0]->{'long_title'} is placed in Excel files and is used as the
+## header for plots created with Graph.pm, both of which more than likely do
+## not support localization.
+##
+my @Fields = (
+           { name => 'problem_num',
+             title => 'P#',
+             align => 'right',
+             color => '#FFFFE6' },
+           { name   => 'container',
+             title  => 'Sequence or Folder',
+             align  => 'left',
+             color  => '#FFFFE6',
+             sortable => 'yes' },
+           { name   => 'title',
+             title  => 'Title',
+             align  => 'left',
+             color  => '#FFFFE6',
+             special  => 'link',
+             sortable => 'yes', },
+           { name   => 'part', 
+             title  => 'Part',
+             align  => 'left',
+             color  => '#FFFFE6',
+             },
+           { name   => 'num_students',
+             title  => '#Stdnts',
+             align  => 'right',
+             color  => '#EEFFCC',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Number of Students Attempting Problem' },
+           { name   => 'tries',
+             title  => 'Tries',
+             align  => 'right',
+             color  => '#EEFFCC',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Total Number of Tries' },
+           { name   => 'max_tries',
+             title  => 'Max Tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Maximum Number of Tries' },
+           { name   => 'min_tries',
+             title  => 'Min Tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Minumum Number of Tries' },
+           { name   => 'mean_tries',
+             title  => 'Mean Tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%5.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Average Number of Tries' },
+           { name   => 'std_tries',
+             title  => 'S.D. tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%5.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Standard Deviation of Number of Tries' },
+           { name   => 'skew_tries',
+             title  => 'Skew Tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%5.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Skew of Number of Tries' },
+           { name   => 'num_solved',
+             title  => '#YES',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%4.1f',#             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Number of Students able to Solve' },
+           { name   => 'num_override',
+             title  => '#yes',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%4.1f',#             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Number of Students given Override' },
+           { name   => 'num_wrong',
+             title  => '#Wrng',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%4.1f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Percent of students whose final answer is wrong' },
+           { name   => 'deg_of_diff',
+             title  => 'DoDiff',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%5.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Degree of Difficulty'.
+                           '[ 1 - ((#YES+#yes) / Tries) ]'},
+           { name   => 'deg_of_disc',
+             title  => 'DoDisc',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%4.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Degree of Discrimination' },
+);
+
+###############################################
+###############################################
 
-sub LoadDoDiffFile {
-    my $file="/home/minaeibi/183d.txt";
-    open(FILEID, "<$file");
-    my $line=<FILEID>;
-    my %DoDiff=();
-    my @Act=split('&',$line);
-    
-#    $r->print('<br>'.$#Act);
-    for(my $n=0;$n<=$#Act;$n++){
-       my ($res,$Degree)=split('@',$Act[$n]);
-      $DoDiff{$res}=$Degree;
-    }
-
-    return \%DoDiff;
-}
-
-sub LoadClassFile {
-    my $file="/home/minaeibi/class.txt";
-    open(FILEID, "<$file");
-    my $line;
-    my %Grade=();
-    while ($line=<FILEID>) {
-        my ($id,$ex1,$ex2,$ex3,$ex4,$hw,$final,$grade)=split(' ',$line);
-        $Grade{$id}=$grade;
-    }
-    return \%Grade;
-}
-
-#------- Classification  
-sub Classify {
-    my ($DiscFac, $students)=@_;
-    my ($fileGrade) = &LoadClassFile();
-    my $Count=0;
-    my @List=();
-    my @LS=();
-    my @LF=();
-    my @LM=();
-    my $cf=0;
-    my $cs=0;
-    my $cm=0;
-    foreach (keys(%$DiscFac)){  
-	my @l=split(/\:/,$_);
-	if (!($students->{$l[1]})) {next;}
-	my $Grade=$fileGrade->{$students->{$l[1]}};
-	if( $Grade > 3 ) {
-	    $cs++;
-	    push(@LS,("$l[6],$l[5],$l[4],$l[7],$l[8],$l[9],Successful"));
-	} elsif ( $Grade > 2 ) {
-	    $cm++;
-	    push(@LM,("$l[6],$l[5],$l[4],$l[7],$l[8],$l[9],Average"));
-	} else {
-	    $cf++;
-	    push(@LF,("$l[6],$l[5],$l[4],$l[7],$l[8],$l[9],Failed"));
-	}
-    }
-    my $Str = '';
-    for(my $n=0;$n<$cs;$n++){$Str .= '<br>'.$LS[$n];}
-    for(my $n=0;$n<$cm;$n++){$Str .= '<br>'.$LM[$n];}  
-    for(my $n=0;$n<$cf;$n++){$Str .= '<br>'.$LF[$n];}
+=pod 
 
-    return $Str;
-} 
+=item &CreateInterface()
 
-sub ProcAct {
-    # return;
-    my ($Act,$Submit)=@_;
-    my @Act=split(/\@/,$Act);
-    @Act = sort(@Act);
+Create the main intereface for the statistics page.  Allows the user to
+select sections, maps, and output.
 
-    ##$r->print('<br>'.$#Act);
-    ##for(my $n=0;$n<=$#Act;$n++){
-##	$r->print('<br>n='.$n.')'.$Act[$n]);
-##    }
+=cut
 
-#    my $Beg=$Act[0];
-    my $Dif=$Submit-$Act[0];
-    $Dif = ($Dif>0) ? ($Dif/3600) : 0; 
+###############################################
+###############################################
+sub CreateInterface {
+    my $Str = '';
+    $Str .= &Apache::lonhtmlcommon::breadcrumbs
+        (undef,'Overall Problem Statistics','Statistics_Overall_Key');
+    $Str .= '<table cellspacing="5">'."\n";
+    $Str .= '<tr>';
+    $Str .= '<td align="center"><b>'.&mt('Sections').'</b></td>';
+    $Str .= '<td align="center"><b>'.&mt('Enrollment Status').'</b></td>';
+    $Str .= '<td align="center"><b>'.&mt('Sequences and Folders').'</b></td>';
+    $Str .= '<td rowspan="2">'.
+        &Apache::lonstathelpers::limit_by_time_form().'</td>';
+    $Str .= '</tr>'."\n";
+    #
+    $Str .= '<tr><td align="center">'."\n";
+    $Str .= &Apache::lonstatistics::SectionSelect('Section','multiple',5);
+    $Str .= '</td><td align="center">';
+    $Str .= &Apache::lonhtmlcommon::StatusOptions(undef,undef,5);
+    $Str .= '</td><td align="center">';
+    #
+    my $only_seq_with_assessments = sub { 
+        my $s=shift;
+        if ($s->{'num_assess'} < 1) { 
+            return 0;
+        } else { 
+            return 1;
+        }
+    };
+    $Str .= &Apache::lonstatistics::MapSelect('Maps','multiple,all',5,
+                                              $only_seq_with_assessments);
+    $Str .= '</td></tr>'."\n";
+    $Str .= '</table>'."\n";
+    $Str .= '<input type="submit" name="GenerateStatistics" value="'.
+        &mt('Generate Statistics').'" />';
+    $Str .= '&nbsp;'x5;
+    $Str .= 'Plot '.&plot_dropdown().('&nbsp;'x10);
+    $Str .= '<input type="submit" name="ClearCache" value="'.
+        &mt('Clear Caches').'" />';
+    $Str .= '&nbsp;'x5;
+    $Str .= '<input type="submit" name="UpdateCache" value="'.
+        &mt('Update Student Data').'" />';
+    $Str .= '&nbsp;'x5;
+    $Str .= '<input type="submit" name="Excel" value="'.
+        &mt('Produce Excel Output').'" />';
+    $Str .= '&nbsp;'x5;
+    return $Str;
+}
 
-#    $r->print('<br>Access Number = '.$#Act.'<br>Submit Time='.$Submit.'<br>First Access='.$Act[0].'<br>Last Access='.$Act[$#Act].'<br> Submit - First = <b>'.$Dif.'</b>');
+###############################################
+###############################################
 
+=pod 
 
-#time spent for solving the problem           
-#    $r->print('<br>Def'.($Act[$#Act-1]-$Act[0]));
+=item &BuildProblemStatisticsPage()
 
-    return $Dif;
-}
+Main interface to problem statistics.
 
-sub LoadActivityLog {
-#    my $CacheDB = "/home/minaeibi/act183.log.cache";
-    my $CacheDB = "/home/httpd/perl/tmp/act183.log.cache";
+=cut
 
-    my %Activity;
-    if (-e "$CacheDB") {
-	if (tie(%Activity,'GDBM_File',"$CacheDB",&GDBM_READER,0640)) {
-	    return;
-        }
-        else {
-#	    $r->print("Unable to tie log Cache hash to db file");
+###############################################
+###############################################
+sub BuildProblemStatisticsPage {
+    my ($r,$c)=@_;
+    #
+    my %Saveable_Parameters = ('Status' => 'scalar',
+                               'statsoutputmode' => 'scalar',
+                               'Section' => 'array',
+                               'StudentData' => 'array',
+                               'Maps' => 'array');
+    &Apache::loncommon::store_course_settings('statistics',
+                                              \%Saveable_Parameters);
+    &Apache::loncommon::restore_course_settings('statistics',
+                                                \%Saveable_Parameters);
+    #
+    &Apache::lonstatistics::PrepareClasslist();
+    #
+    # Clear the package variables
+    undef(@StatsArray);
+    #
+    # Finally let the user know we are here
+    my $interface = &CreateInterface();
+    $r->print($interface);
+    $r->print('<input type="hidden" name="sortby" value="'.$ENV{'form.sortby'}.
+              '" />');
+    #
+    if (! exists($ENV{'form.statsfirstcall'})) {
+        $r->print('<input type="hidden" name="statsfirstcall" value="yes" />');
+        $r->print('<h3>'.
+                  &mt('Press "Generate Statistics" when you are ready.').
+                  '</h3><p>'.
+                  &mt('It may take some time to update the student data '.
+                      'for the first analysis.  Future analysis this session '.
+                      ' will not have this delay.').
+                  '</p>');
+        return;
+    } elsif ($ENV{'form.statsfirstcall'} eq 'yes' || 
+             exists($ENV{'form.UpdateCache'}) ||
+             exists($ENV{'form.ClearCache'}) ) {
+        $r->print('<input type="hidden" name="statsfirstcall" value="no" />');
+        &Apache::lonstatistics::Gather_Student_Data($r);
+    } else {
+        $r->print('<input type="hidden" name="statsfirstcall" value="no" />');
+    }
+    $r->rflush();
+    #
+    # This probably does not need to be done each time we are called, but
+    # it does not slow things down noticably.
+    &Apache::loncoursedata::populate_weight_table();
+    if (exists($ENV{'form.Excel'})) {
+        &Excel_output($r);
+    } else {
+        my $sortby = $ENV{'form.sortby'};
+        $sortby = 'container' if (! defined($sortby) || $sortby =~ /^\s*$/);
+        my $plot = $ENV{'form.plot'};
+        &Apache::lonnet::logthis('form.plot = '.$plot);
+        if ($sortby eq 'container' && ! defined($plot)) {
+            &output_html_by_sequence($r);
+        } else {
+            if (defined($plot)) {
+                &Apache::lonnet::logthis('calling plot routine');
+                &make_plot($r,$plot);
+            }
+            &output_html_stats($r);
         }
     }
-    else {
-	if (tie(%Activity,'GDBM_File',$CacheDB,&GDBM_WRCREAT,0640)) {
-	    foreach (keys %Activity) {delete $Activity{$_};}
-	    &Build_log(\%Activity); 
-	}
-        else {
-#	    $r->print("Unable to tie log Build hash to db file");
+    return;
+}
+
+##########################################################
+##########################################################
+##
+## HTML output routines
+##
+##########################################################
+##########################################################
+sub output_html_by_sequence {
+    my ($r) = @_;
+    my $c = $r->connection();
+    $r->print(&html_preamble());
+    #
+    foreach my $seq (&Apache::lonstatistics::Sequences_with_Assess()) {
+        last if ($c->aborted);
+        next if ($seq->{'num_assess'} < 1);
+        $r->print("<h3>".$seq->{'title'}."</h3>".
+                  '<table border="0"><tr><td bgcolor="#777777">'."\n".
+                  '<table border="0" cellpadding="3">'."\n".
+                  '<tr bgcolor="#FFFFE6">'.
+                  &statistics_table_header('no container')."</tr>\n");
+        my @Data = &compute_statistics_on_sequence($seq);
+        foreach my $data (@Data) {
+            $r->print('<tr>'.&statistics_html_table_data($data,
+                                                         'no container').
+                      "</tr>\n");
         }
+        $r->print('</table>'."\n".'</table>'."\n");
+        $r->rflush();
     }
-    return \%Activity;
+    return;
 }
 
-sub Build_log {
-    my ($Activity)=@_;
-    my $file="/home/minaeibi/act183.log";
-    open(FILEID, "<$file");
-    my $line;
+sub output_html_stats {
+    my ($r)=@_;
+    &compute_all_statistics($r);
+    $r->print(&html_preamble());
+    &sort_data($ENV{'form.sortby'});
+    #
     my $count=0;
-    while ($line=<FILEID>) {
-	my ($time,$machine,$what)=split(':',$line);
-	$what=&Apache::lonnet::unescape($what);
-	my @accesses=split('&',$what);
-	           
-	foreach my $access (@accesses) {
-
-	    $count++;
-
-	    my ($date,$resource,$who,$domain,$post,@posts)=split(':',$access);
-	    if (!$resource) { next; }
-	    my $res=&Apache::lonnet::unescape($resource);
-	    if (($res =~ /\.problem/)) {
-		$Activity->{$who.':'.$res}.=$date.'@';
-                #$r->print('<br>'.$time.':'.$who.'---'.$res);
-		&Update_PrgInit($count);
-
-	    }
-	}
-    }
-
-# my $c=1;
-# foreach (sort keys %Activity) {
-#     $r->print('<br>'.$c.')'.$_.' ... '.$Activity{$_});
-#     $c++;
-# }
-
-}
-
-sub Activity {
-    my $file="/home/minaeibi/activity.log";
-    my $userid='adamsde1';
-#    $r->print("<br>Using $file");
-#    $r->rflush();
-    open(FILEID, "<$file");
-    my $line;
-    my @allaccess;
-    my $Count=0;
-    while ($line=<FILEID>) {
-	my ($time,$machine,$what)=split(':',$line);
-	$what=&Apache::lonnet::unescape($what);
-	my @accesses=split('&',$what);
-	foreach my $access (@accesses) {
-	    my ($date,$resource,$who,$domain,$post,@posts)=split(':',$access);
-	    #if ($who ne $userid) { next; }
-	    if (!$resource) { next; }
-	    my $res=&Apache::lonnet::unescape($resource);
-	    if (($res =~ /\.(sequence|problem|htm|html|page)/)) {
-	    	$Count++;
-###888		$r->print("<br>$Count) ".localtime($date).": $who --> $res");
-#	        if ($post) { 
-#		    $Count++;
-#		    $r->print("<br><b>$Count) Sent data ".join(':',
-#                              &Apache::lonnet::unescape(@posts)).'</b>');
-#		}
-###888		$r->rflush();
-	    }
-	    #push (@allaccess,unescape($access));
-	    #print $machine;
-	}
-    }
-#    @allaccess=sort(@allaccess);
-#    $Count=0;
-#    foreach my $access (@allaccess) {
-#	my ($date,$resource,$who,$domain,$post,@posts)=split(':',$access);
-#	$Count++;
-#	$r->print("<br>$Count) $date: $who --> $resource");
-#	$r->rflush();
-#	if ($post) { 
-#	    $r->print("<br><b>Sent data ".join(':',unescape(@posts)).'</b>');
-#	}
-#    }
-}
-
-#---- END Activity log ---------------------------------------------------
-
-#---- Problem Statistics Web Page ---------------------------------------
-
-#------- Processing upperlist and lowerlist according to each problem
-sub ProcessDiscriminant {
-    my ($List) = @_;
-    my @sortedList = sort (@$List);
-    my $Count = scalar @sortedList;
-    my $Problem;
-    my @Dis;
-    my $Slvd=0;
-    my $tmp;
-    my $Sum1=0;
-    my $Sum2=0;
-    my $nIndex=0;
-    my $nStudent=0;
-    my %Proc=undef;
-    while ($nIndex<$Count) {
-	($Problem,$tmp)=split(/\=/,$sortedList[$nIndex]);
-	@Dis=split(/\+/,$tmp);
-	my $Temp = $Problem;
-	do {
-	    $nIndex++;
-	    $nStudent++;
-	    $Sum1 += $Dis[0];
-	    $Sum2 += $Dis[1];
-	    ($Problem,$tmp)=split(/\=/,$sortedList[$nIndex]);
-	    @Dis=split(/\+/,$tmp);
-	} while ( $Problem eq $Temp && $nIndex < $Count );
-#	$Proc{$Temp}=($Sum1/$nStudent).':'.$nStudent;
-	$Proc{$Temp}=($Sum1/$nStudent).':'.($Sum2/$nStudent);
-#       $r->print("$nIndex) $Temp --> ($nStudent) $Proc{$Temp} <br>");
-	$Sum1=0;
-	$Sum2=0;
-	$nStudent=0;
-    }
-
-    return %Proc;
-}
-
-#------- Creating Discimination factor   
-sub Discriminant {
-    my ($discriminantFactor)=@_;
-    my @discriminantKeys=keys(%$discriminantFactor);
-    my $Count = scalar @discriminantKeys;
-
-    my $UpCnt = int(0.27*$Count);
-    my $low=0;
-    my $up=$Count-$UpCnt;
-    my @UpList=();
-    my @LowList=();
-
-    $Count=0;
-    foreach my $key (sort(@discriminantKeys)) { 
-	$Count++;    
-	if($low < $UpCnt || $Count > $up) {
-            $low++;
-            my $str=$discriminantFactor->{$key};
-            foreach(split(/\:/,$str)){
-                if($_) {
-                    if($low<$UpCnt) { push(@LowList,$_); }
-                    else            { push(@UpList,$_);  }
-                }
-            }
+    foreach my $data (@StatsArray) {
+        if ($count++ % 50 == 0) {
+            $r->print("</table>\n</table>\n");
+            $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n".
+                      '<table border="0" cellpadding="3">'."\n".
+                      '<tr bgcolor="#FFFFE6">'.
+                      '<tr bgcolor="#FFFFE6">'.
+                      &statistics_table_header().
+                      "</tr>\n");
         }
+        $r->print('<tr>'.&statistics_html_table_data($data)."</tr>\n");
     }
-    my %DisUp =  &ProcessDiscriminant(\@UpList);
-    my %DisLow = &ProcessDiscriminant(\@LowList);
+    $r->print("</table>\n</table>\n");
+    return;
+}
+
 
-    return (\%DisUp, \%DisLow);
+sub html_preamble {
+    my $Str='';
+    $Str .= "<h2>".
+        $ENV{'course.'.$ENV{'request.course.id'}.'.description'}.
+        "</h2>\n";
+    my ($starttime,$endtime) = &Apache::lonstathelpers::get_time_limits();
+    if (defined($starttime) || defined($endtime)) {
+        # Inform the user what the time limits on the data are.
+        $Str .= '<h3>'.&mt('Statistics on submissions from [_1] to [_2]',
+                           &Apache::lonlocal::locallocaltime($starttime),
+                           &Apache::lonlocal::locallocaltime($endtime)
+                           ).'</h3>';
+    }
+    $Str .= "<h3>".&mt('Compiled on [_1]',
+                       &Apache::lonlocal::locallocaltime(time))."</h3>";
+    return $Str;
 }
 
-   
-sub NumericSort {          
-    $a <=> $b;
+
+###############################################
+###############################################
+##
+## Misc HTML output routines
+##
+###############################################
+###############################################
+sub statistics_html_table_data {
+    my ($data,$options) = @_;
+    my $row = '';
+    foreach my $field (@Fields) {
+        next if ($options =~ /no $field->{'name'}/);
+        $row .= '<td bgcolor="'.$field->{'color'}.'"';
+        if (exists($field->{'align'})) {
+            $row .= ' align="'.$field->{'align'}.'"';
+            }
+        $row .= '>';
+        if (exists($field->{'special'}) && $field->{'special'} eq 'link') {
+            $row .= '<a href="'.$data->{$field->{'name'}.'.link'}.'">';
+        }
+        if (exists($field->{'format'})) {
+            $row .= sprintf($field->{'format'},$data->{$field->{'name'}});
+        } else {
+            $row .= $data->{$field->{'name'}};
+        }
+        if (exists($field->{'special'}) && $field->{'special'} eq 'link') {
+            $row.= '</a>';
+        }
+        $row .= '</td>';
+    }
+    return $row;
 }
 
+sub statistics_table_header {
+    my ($options) = @_;
+    my $header_row;
+    foreach my $field (@Fields) {
+        next if ($options =~ /no $field->{'name'}/);
+        $header_row .= '<th>';
+        if (exists($field->{'sortable'}) && $field->{'sortable'} eq 'yes') {
+            $header_row .= '<a href="javascript:'.
+                'document.Statistics.sortby.value='."'".$field->{'name'}."'".
+                    ';document.Statistics.submit();">';
+        }
+        $header_row .= &mt($field->{'title'});
+        if ($options =~ /sortable/) {
+            $header_row.= '</a>';
+        }
+        if ($options !~ /no plots/        && 
+            exists($field->{'graphable'}) && 
+            $field->{'graphable'} eq 'yes') {
+            $header_row.=' (';
+            $header_row .= '<a href="javascript:'.
+                "document.Statistics.plot.value='$field->{'name'}'".
+                    ';document.Statistics.submit();">';
+            $header_row .= &mt('plot').'</a>)';
+        }
+        $header_row .= '</th>';
+    }
+    return $header_row;
+}
 
-sub CreateProblemStatisticsTableHeading {
-    my ($displayFormat,$sequenceSource,$sequenceTitle,$headings,$r)=@_;
-    if($displayFormat eq 'Display CSV Format') {
-        $r->print('<br>"'.$sequenceTitle.'","');
-        $r->print($sequenceSource.'"');
-	return;
+####################################################
+####################################################
+##
+##    Plotting Routines
+##
+####################################################
+####################################################
+sub make_plot {
+    my ($r,$plot) = @_;
+    &compute_all_statistics($r);
+    &sort_data($ENV{'form.sortby'});
+    if ($plot eq 'degrees') {
+        &degrees_plot($r);
+    } else {
+        &make_single_stat_plot($r,$plot);
     }
+    return;
+}
 
-    $r->print('<br><a href="'.$sequenceSource.
-              '" target="_blank">'.$sequenceTitle.'</a>');
+sub make_single_stat_plot {
+    my ($r,$datafield) = @_;
+    #
+    my $title; my $yaxis;
+    foreach my $field (@Fields) {
+        next if ($field->{'name'} ne $datafield);
+        $title = $field->{'long_title'};
+        $yaxis = $field->{'title'};
+        last;
+    }
+    if ($title eq '' || $yaxis eq '') {
+        # datafield is something we do not know enough about to plot
+        $r->print('<h3>'.
+                  &mt('Unable to plot the requested statistic.').
+                  '</h3>');
+        return;
+    }
+    #
+    # Build up the data sets to plot
+    my @Labels; 
+    my @Data;
+    my $max = 1;
+    foreach my $data (@StatsArray) {
+        push(@Labels,$data->{'problem_num'});
+        push(@Data,$data->{$datafield});
+        if ($data->{$datafield}>$max) {
+            $max = $data->{$datafield};
+        }
+    }
+    foreach (1,2,3,4,5,10,15,20,25,40,50,75,100,150,200,250,300,500,600,750,
+             1000,1500,2000,2500,3000,3500,4000,5000,7500,10000,15000,20000) {
+        if ($max <= $_) {
+            $max = $_;
+            last;
+        }
+    }
+    if ($max > 20000) {
+        $max = 10000*(int($max/10000)+1);
+    }
+    #
+    $r->print("<p>".&Apache::loncommon::DrawBarGraph($title,
+                                                     'Problem Number',
+                                                     $yaxis,
+                                                     $max,
+                                                     undef, # colors
+                                                     \@Labels,
+                                                     \@Data)."</p>\n");
+    return;
+}
 
-    my $Result = "\n".'<table border=2><tr><th>P#</th>'."\n";
-    for(my $nIndex=0; $nIndex < (scalar (keys %$headings)); $nIndex++) { 
-	$Result .= '<th>'.'<input type="submit" name="';
-        $Result .= 'ProblemStatisticsHeading" value="';
-        $Result .= $headings->{$nIndex}.'" />'.'</th>'."\n";
+sub degrees_plot {
+    my ($r)=@_;
+    my $count = scalar(@StatsArray);
+    my $width = 50 + 10*$count;
+    $width = 300 if ($width < 300);
+    my $height = 300;
+    my $plot = '';
+    my $ymax = 0;
+    my $ymin = 0;
+    my @Disc; my @Diff; my @Labels;    
+    foreach my $data (@StatsArray) {
+        push(@Labels,$data->{'problem_num'});
+        my $disc = $data->{'deg_of_disc'};
+        my $diff = $data->{'deg_of_diff'};
+        push(@Disc,$disc);
+        push(@Diff,$diff);
+        #
+        $ymin = $disc if ($ymin > $disc);
+        $ymin = $diff if ($ymin > $diff);
+        $ymax = $disc if ($ymax < $disc);
+        $ymax = $diff if ($ymax < $diff);
+    }
+    #
+    # Make sure we show relevant information.
+    if ($ymin < 0) {
+        if (abs($ymin) < 0.05) {
+            $ymin = 0;
+        } else {
+            $ymin = -1;
+        }
     }
-    $Result .= "\n".'</tr>'."\n";    
-    $r->print($Result);
-    $r->rflush();
+    if ($ymax > 0) {
+        if (abs($ymax) < 0.05) {
+            $ymax = 0;
+        } else {
+            $ymax = 1;
+        }
+    }
+    #
+    my $xmax = $Labels[-1];
+    if ($xmax > 50) {
+        if ($xmax % 10 != 0) {
+            $xmax = 10 * (int($xmax/10)+1);
+        }
+    } else {
+        if ($xmax % 5 != 0) {
+            $xmax = 5 * (int($xmax/5)+1);
+        }
+    }
+    #
+    my $discdata .= '<data>'.join(',',@Labels).'</data>'.$/.
+                    '<data>'.join(',',@Disc).'</data>'.$/;
+    #
+    my $diffdata .= '<data>'.join(',',@Labels).'</data>'.$/.
+                    '<data>'.join(',',@Diff).'</data>'.$/;
+    #
+    $plot=<<"END";
+<gnuplot 
+    texfont="10"
+    fgcolor="x000000"
+    plottype="Cartesian"
+    font="large"
+    grid="on"
+    align="center"
+    border="on"
+    transparent="on"
+    alttag="Sample Plot"
+    samples="100"
+    bgcolor="xffffff"
+    height="$height"
+    width="$width">
+    <key 
+        pos="top right"
+        title=""
+        box="off" />
+    <title>Degree of Discrmination and Degree of Difficulty</title>
+    <axis xmin="0" ymin="$ymin" xmax="$xmax" ymax="$ymax" color="x000000" />
+    <xlabel>Problem Number</xlabel>
+    <curve 
+        linestyle="linespoints" 
+        name="DoDisc" 
+        pointtype="0" 
+        color="x000000">
+        $discdata
+    </curve>
+    <curve 
+        linestyle="linespoints" 
+        name="DoDiff" 
+        pointtype="0" 
+        color="xFF0000">
+        $diffdata
+    </curve>
+</gnuplot>
+END
+    my $plotresult = 
+        '<p>'.&Apache::lonxml::xmlparse($r,'web',$plot).'</p>'.$/;
+    $r->print($plotresult);
+    return;
+}
+
+sub plot_dropdown {
+    my $current = '';
+    #
+    if (defined($ENV{'form.plot'})) {
+        $current = $ENV{'form.plot'};
+    }
+    #
+    my @Additional_Plots = (
+                            { graphable=>'yes',
+                              name => 'degrees',
+                              title => 'DoDisc and DoDiff' });
+    #
+    my $Str= "\n".'<select name="plot" size="1">';
+    $Str .= '<option name="none"></option>'."\n";
+    $Str .= '<option name="none2">none</option>'."\n";
+    foreach my $field (@Fields,@Additional_Plots) {
+        if (! exists($field->{'graphable'}) ||
+            $field->{'graphable'} ne 'yes') {
+            next;
+        }
+        $Str .= '<option value="'.$field->{'name'}.'"';
+        if ($field->{'name'} eq $current) {
+            $Str .= ' selected ';
+        }
+        $Str.= '>'.&mt($field->{'title'}).'</option>'."\n";
+    }
+    $Str .= '</select>'."\n";
+    return $Str;
 }
 
-sub CloseTable {
-    my ($cache,$r)=@_;
-    if($cache->{'DisplayFormat'} eq 'Display CSV Format') {
-	return;
-    }    
-    $r->print("\n".'</table>'."\n");
+###############################################
+###############################################
+##
+## Excel output routines
+##
+###############################################
+###############################################
+sub Excel_output {
+    my ($r) = @_;
+    $r->print('<h2>'.&mt('Preparing Excel Spreadsheet').'</h2>');
+    ##
+    ## Compute the statistics
+    &compute_all_statistics($r);
+    my $c = $r->connection;
+    return if ($c->aborted());
+    ##
+    ## Create the excel workbook
+    my $filename = '/prtspool/'.
+        $ENV{'user.name'}.'_'.$ENV{'user.domain'}.'_'.
+        time.'_'.rand(1000000000).'.xls';
+    my ($starttime,$endtime) = &Apache::lonstathelpers::get_time_limits();
+    #
+    # Create sheet
+    my $excel_workbook = Spreadsheet::WriteExcel->new('/home/httpd'.$filename);
+    #
+    # Check for errors
+    if (! defined($excel_workbook)) {
+        $r->log_error("Error creating excel spreadsheet $filename: $!");
+        $r->print(&mt("Problems creating new Excel file.  ".
+                  "This error has been logged.  ".
+                  "Please alert your LON-CAPA administrator."));
+        return 0;
+    }
+    #
+    # The excel spreadsheet stores temporary data in files, then put them
+    # together.  If needed we should be able to disable this (memory only).
+    # The temporary directory must be specified before calling 'addworksheet'.
+    # File::Temp is used to determine the temporary directory.
+    $excel_workbook->set_tempdir($Apache::lonnet::tmpdir);
+    #
+    # Add a worksheet
+    my $sheetname = $ENV{'course.'.$ENV{'request.course.id'}.'.description'};
+    if (length($sheetname) > 31) {
+        $sheetname = substr($sheetname,0,31);
+    }
+    my $excel_sheet = $excel_workbook->addworksheet(
+        &Apache::loncommon::clean_excel_name($sheetname));
+    ##
+    ## Begin creating excel sheet
+    ##
+    my ($rows_output,$cols_output) = (0,0);
+    #
+    # Put the course description in the header
+    $excel_sheet->write($rows_output,$cols_output++,
+                   $ENV{'course.'.$ENV{'request.course.id'}.'.description'});
+    $cols_output += 3;
+    #
+    # Put a description of the sections listed
+    my $sectionstring = '';
+    my @Sections = @Apache::lonstatistics::SelectedSections;
+    if (scalar(@Sections) > 1) {
+        if (scalar(@Sections) > 2) {
+            my $last = pop(@Sections);
+            $sectionstring = "Sections ".join(', ',@Sections).', and '.$last;
+        } else {
+            $sectionstring = "Sections ".join(' and ',@Sections);
+        }
+    } else {
+        if ($Sections[0] eq 'all') {
+            $sectionstring = "All sections";
+        } else {
+            $sectionstring = "Section ".$Sections[0];
+        }
+    }
+    $excel_sheet->write($rows_output,$cols_output++,$sectionstring);
+    $cols_output += scalar(@Sections);
+    #
+    # Time restrictions
+    my $time_string;
+    if (defined($starttime)) {
+        # call localtime but not lonlocal:locallocaltime because excel probably
+        # cannot handle localized text.  Probably.
+        $time_string .= 'Data collected from '.localtime($time_string);
+        if (defined($endtime)) {
+            $time_string .= ' to '.localtime($endtime);
+        }
+        $time_string .= '.';
+    } elsif (defined($endtime)) {
+        # See note above about lonlocal:locallocaltime
+        $time_string .= 'Data collected before '.localtime($endtime).'.';
+    }
+    #
+    # Put the date in there too
+    $excel_sheet->write($rows_output,$cols_output++,
+                        'Compiled on '.localtime(time));
+    #
+    $rows_output++; 
+    $cols_output=0;
+    #
+    # Long Headers
+    foreach my $field (@Fields) {
+        next if ($field->{'name'} eq 'problem_num');
+        if (exists($field->{'long_title'})) {
+            $excel_sheet->write($rows_output,$cols_output++,
+                                $field->{'long_title'});
+        } else {
+            $excel_sheet->write($rows_output,$cols_output++,'');
+        }
+    }
+    $rows_output++;
+    $cols_output=0;
+    # Brief headers
+    foreach my $field (@Fields) {
+        next if ($field->{'name'} eq 'problem_num');
+        # Use english for excel as I am not sure how well excel handles 
+        # other character sets....
+        $excel_sheet->write($rows_output,$cols_output++,$field->{'title'});
+    }
+    $rows_output++;
+    foreach my $data (@StatsArray) {
+        $cols_output=0;
+        foreach my $field (@Fields) {
+            next if ($field->{'name'} eq 'problem_num');
+            $excel_sheet->write($rows_output,$cols_output++,
+                                $data->{$field->{'name'}});
+        }
+        $rows_output++;
+    }
+    #
+    $excel_workbook->close();
+    #
+    # Tell the user where to get their excel file
+    $r->print('<br />'.
+              '<a href="'.$filename.'">'.
+              &mt('Your Excel Spreadsheet').'</a>'."\n");
     $r->rflush();
+    return;
 }
 
-
- 
-# ------ Dump the Student's DB file and handling the data for statistics table 
-sub ExtractStudentData {
-    my ($cache,$name,$list,%Discuss)=@_;
-    my %discriminantFactor;
-
-    my $totalTries = 0;
-    my $totalAwarded = 0;
-    my $tempProblemOrder=0;
-    my $spent=0;
-    my $spent_yes=0;
-    my $TotDiscuss=0;
-    my $TotalOpend = 0;
-    my $ProbSolved = 0;
-    my $ProbTot = 0;
-    my $TotFirst = 0;
-    my $TimeTot = 0;
-    my $Discussed=0;
-
-    foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
-        if($cache->{'ProblemStatisticsMap'} ne 'All Maps'  &&
-           $cache->{'ProblemStatisticsMap'} ne $cache->{$sequence.':title'}) {
-            next;
+##################################################
+##################################################
+##
+## Statistics Gathering and Manipulation Routines
+##
+##################################################
+##################################################
+sub compute_statistics_on_sequence {
+    my ($seq) = @_;
+    my @Data;
+    foreach my $res (@{$seq->{'contents'}}) {
+        next if ($res->{'type'} ne 'assessment');
+        foreach my $part (@{$res->{'parts'}}) {
+            #
+            # This is where all the work happens
+            my $data = &get_statistics($seq,$res,$part,scalar(@StatsArray)+1);
+            push (@Data,$data);
+            push (@StatsArray,$data);
         }
+    }
+    return @Data;
+}
 
-        my $Dis = '';
-        foreach my $problemID (split(':', $cache->{$sequence.':problems'})) {
-            my $problem = $cache->{$problemID.':problem'};
-            my $LatestVersion = $cache->{$name.':version:'.$problem};
-
-            # Output dashes for all the parts of this problem if there
-            # is no version information about the current problem.
-            #if(!$LatestVersion) {
-            #    foreach my $part (split(/\:/,$cache->{$sequence.':'.
-            #                                          $problemID.
-            #                                          ':parts'})) {
-            #        $codes    .= "-,";
-            #        $attempts .= "0,"; 
-            #    }
-            #    next;
-            #}
-
-            my %partData=undef;
-            # Initialize part data, display skips correctly
-            # Skip refers to when a student made no submissions on that
-            # part/problem.
-            foreach my $part (split(/\:/,$cache->{$sequence.':'.
-                                                  $problemID.
-                                                  ':parts'})) {
-                $partData{$part.':tries'}=0;
-                $partData{$part.':code'}='-';
-            }
+sub compute_all_statistics {
+    my ($r) = @_;
+    if (@StatsArray > 0) {
+        # Assume we have already computed the statistics
+        return;
+    }
+    my $c = $r->connection;
+    foreach my $seq (&Apache::lonstatistics::Sequences_with_Assess()) {
+        last if ($c->aborted);
+        next if ($seq->{'num_assess'} < 1);
+        &compute_statistics_on_sequence($seq);
+    }
+}
 
-            # Looping through all the versions of each part, starting with the
-            # oldest version.  Basically, it gets the most recent 
-            # set of grade data for each part.
-	    for(my $Version=1; $Version<=$LatestVersion; $Version++) {
-                foreach my $part (split(/\:/,$cache->{$sequence.':'.
-                                                      $problemID.
-                                                      ':parts'})) {
-
-                    if(!defined($cache->{$name.":$Version:$problem".
-                                               ":resource.$part.solved"})) {
-                        # No grade for this submission, so skip
-                        next;
+sub sort_data {
+    my ($sortkey) = @_;
+    return if (! @StatsArray);
+    #
+    # Sort the data
+    my $sortby = undef;
+    foreach my $field (@Fields) {
+        if ($sortkey eq $field->{'name'}) {
+            $sortby = $field->{'name'};
+        }
+    }
+    if (! defined($sortby) || $sortby eq '' || $sortby eq 'problem_num') {
+        $sortby = 'container';
+    }
+    if ($sortby ne 'container') {
+        # $sortby is already defined, so we can charge ahead
+        if ($sortby =~ /^(title|part)$/i) {
+            # Alpha comparison
+            @StatsArray = sort {
+                lc($a->{$sortby}) cmp lc($b->{$sortby}) ||
+                lc($a->{'title'}) cmp lc($b->{'title'}) ||
+                lc($a->{'part'}) cmp lc($b->{'part'});
+            } @StatsArray;
+        } else {
+            # Numerical comparison
+            @StatsArray = sort {
+                my $retvalue = 0;
+                if ($b->{$sortby} eq 'nan') {
+                    if ($a->{$sortby} ne 'nan') {
+                        $retvalue = -1;
+                    } else {
+                        $retvalue = 0;
                     }
-
-                    my $tries=0;
-                    my $time=0;
-                    my $awarded=0;
-		    $Discussed=0;
-                    my $code='U';
-
-                    $awarded = $cache->{$name.
-                                        "$Version:$problem:resource.".
-                                        "$part.awarded"};
-                    $partData{$part.':awarded'} = ($awarded) ? $awarded : 0;
-                    $totalAwarded += $awarded;
-
-                    $tries = $cache->{$name.":$Version:$problem".
-                                      ":resource.$part.tries"};
-                    $partData{$part.':tries'} = ($tries) ? $tries : 0;
-                    $partData{$part.':wrong'} = $partData{$part.':tries'};
-                    $totalTries += $tries;
-
-                    my $val = $cache->{$name.":$Version:$problem".
-                                       ":resource.$part.solved"};
-                    if    ($val eq 'correct_by_student')   {$code = 'C';} 
-                    elsif ($val eq 'correct_by_override')  {$code = 'O';}
-                    elsif ($val eq 'incorrect_attempted')  {$code = 'I';} 
-                    elsif ($val eq 'incorrect_by_override'){$code = 'I';}
-                    elsif ($val eq 'excused')              {$code = 'x';}
-                    $partData{$part.':code'}=$code;
-
-                    if($partData{$part.':wrong'} ne 0 && 
-                       ($code eq 'C' || $code eq 'O')) {
-                        $partData{$part.':wrong'}--;
+                }
+                if ($a->{$sortby} eq 'nan') {
+                    if ($b->{$sortby} ne 'nan') {
+                        $retvalue = 1;
                     }
                 }
-            }
-
-            # Loop through all the parts for the current problem in the 
-            # correct order and prepare the output
-            foreach (split(/\:/,$cache->{$sequence.':'.$problemID.
-                                         ':parts'})) {
-                my $Yes = 0;
-                if($partData{$_.':code'} eq 'C' || 
-                   $partData{$_.':code'} eq 'O') {
-                    $Yes=1;
+                if ($retvalue eq '0') {
+                    $retvalue = $b->{$sortby} <=> $a->{$sortby}     ||
+                            lc($a->{'title'}) <=> lc($b->{'title'}) ||
+                            lc($a->{'part'})  <=> lc($b->{'part'});
                 }
-                my $ptr = $tempProblemOrder.'&'.$problemID;
+                $retvalue;
+            } @StatsArray;
+        }
+    }
+    #
+    # Renumber the data set
+    my $count;
+    foreach my $data (@StatsArray) {
+        $data->{'problem_num'} = ++$count;
+    }
+    return;
+}
 
-                if($_ > 1) {
-                    $ptr .= "*(part $_)";
-                    $Dis .= '&';
-                }
+########################################################
+########################################################
 
-		my ($pr_no,$dod)=split('&',$ptr);
-#		my $DoDiff=$DoDiff->{$dod};
-#               $r->print('<br>'.$name.'---'.$ptr.'==='.$DoDiff);
-
-                my $Fac = ($partData{$_.':Tries'}) ? 
-                    ($partData{$_.':awarded'}/$partData{$_.':tries'}) : 0;
-                my $DisF;
-                if($Fac > 0 &&  $Fac < 1) { 
-                    $DisF = sprintf( "%.4f", $Fac );
-                } else {
-                    $DisF = $Fac;
-                }
+=pod
 
-                if ($Discuss{"$name:$problem"}) {
-		    $TotDiscuss++;
-                    $Discussed=1;
-                }
-                my $time = $cache->{"$name:$LatestVersion:$problem:timestamp"};
-                $Dis .= $tempProblemOrder.'='.$DisF.'+'.$Yes;
-                $ptr .= '&'.$partData{$_.'.Tries'}.
-                        '&'.$partData{$_.'.Wrongs'}.
-                        '&'.$partData{$_.'.Code'};
-                push (@$list, $ptr."&$Discussed");
+=item &get_statistics()
 
-####		if ($DoDiff>0.85) {
+Wrapper routine from the call to loncoursedata::get_problem_statistics.  
+Calls lonstathelpers::get_time_limits() to limit the data set by time
+and &compute_discrimination_factor
 
-                $TimeTot += $time;
+Inputs: $sequence, $resource, $part, $problem_num
 
-                if ($Yes==1 && $partData{$_.'.Tries'}==1) {
-		    $TotFirst++;
-                }
-#		my $Acts= $Activity->{$name.':'.$problem};
-#		if ($Acts) {
-#		    my $Pt=&ProcAct( $Acts, $time );
-		    #my ($spe,$beg) = split(/\+/,$Pt);
-#                    my $spe= $Pt;
-#		    if ($Yes==1) {$spent_yes += $spe;}
-#		    $spent += $spe;
-		    #$Beg += $beg;
-#                   $r->print('<br>'.$name.'---'.$problem.'---'.$spe);
-#		}
-		$TotalOpend++;
-		$ProbTot++;
+Returns: Hash reference with statistics data from 
+loncoursedata::get_problem_statistics.
 
-                $tempProblemOrder++;
-            }
-        }
-	my $pstr;
-        if($totalTries) {
-	    my $DisFac = ($totalAwarded/$totalTries);
-	    my $DisFactor = sprintf( "%.4f", $DisFac );
-            my $TS = sprintf( "%.2f", $spent );
-            my $TS_yes = sprintf( "%.2f", $spent_yes );
-	   # $DiscFac{$DisFactor}=$Dis;
-	    $pstr=$DisFactor.':'.$name.':'.$ProbTot.':'.$TotalOpend.':'.
-                  $totalTries.':'.$ProbSolved.':'.$TotFirst.':'.
-                  $TS_yes.':'.$TS.':'.$TotDiscuss;
-	    $discriminantFactor{$pstr}=$Dis;
-	}
-    }
+=cut
 
-    return (\%discriminantFactor);
+########################################################
+########################################################
+sub get_statistics {
+    my ($sequence,$resource,$part,$problem_num) = @_;
+    #
+    my ($starttime,$endtime) = &Apache::lonstathelpers::get_time_limits();
+    my $symb = $resource->{'symb'};
+    my $courseid = $ENV{'request.course.id'};
+    #
+    my $data = &Apache::loncoursedata::get_problem_statistics
+                        (\@Apache::lonstatistics::SelectedSections,
+                         $Apache::lonstatistics::enrollment_status,
+                         $symb,$part,$courseid,$starttime,$endtime);
+    $data->{'part'}        = $part;
+    $data->{'problem_num'} = $problem_num;
+    $data->{'container'}   = $sequence->{'title'};
+    $data->{'title'}       = $resource->{'title'};
+    $data->{'title.link'}  = $resource->{'src'}.'?symb='.
+        &Apache::lonnet::escape($resource->{'symb'});
+    #
+    $data->{'deg_of_disc'} = &compute_discrimination_factor($resource,$part,$sequence);
+    return $data;
 }
 
 
+###############################################
+###############################################
+
 =pod
-sub MySort {          
-    if ( $Pos > 0 ) {
-	if ($ENV{'form.order'} eq 'Descending') {$b <=> $a;}
-	else { $a <=> $b; }
-    }
-    else {
-	if ($ENV{'form.order'} eq 'Descending') {$b cmp $a;}
-	else { $a cmp $b; }
+
+=item &compute_discrimination_factor()
+
+Inputs: $Resource, $Sequence
+
+Returns: integer between -1 and 1
+
+=cut
+
+###############################################
+###############################################
+sub compute_discrimination_factor {
+    my ($resource,$part,$sequence) = @_;
+    my @Resources;
+    foreach my $res (@{$sequence->{'contents'}}) {
+        next if ($res->{'symb'} eq $resource->{'symb'});
+        push (@Resources,$res->{'symb'});
+    }
+    #
+    # rank
+    my $ranking = 
+        &Apache::loncoursedata::rank_students_by_scores_on_resources
+        (\@Resources,
+         \@Apache::lonstatistics::SelectedSections,
+         $Apache::lonstatistics::enrollment_status,undef);
+    #
+    # compute their percent scores on the problems in the sequence,
+    my $number_to_grab = int(scalar(@{$ranking})/4);
+    my $num_students = scalar(@{$ranking});
+    my @BottomSet = map { $_->[&Apache::loncoursedata::RNK_student()]; 
+                      } @{$ranking}[0..$number_to_grab];
+    my @TopSet    = 
+        map { 
+            $_->[&Apache::loncoursedata::RNK_student()]; 
+          } @{$ranking}[($num_students-$number_to_grab)..($num_students-1)];
+    my ($bottom_sum,$bottom_max) = 
+        &Apache::loncoursedata::get_sum_of_scores($resource,$part,\@BottomSet);
+    my ($top_sum,$top_max) = 
+        &Apache::loncoursedata::get_sum_of_scores($resource,$part,\@TopSet);
+    my $deg_of_disc;
+    if ($top_max == 0 || $bottom_max==0) {
+        $deg_of_disc = 'nan';
+    } else {
+        $deg_of_disc = ($top_sum/$top_max) - ($bottom_sum/$bottom_max);
     }
+    #&Apache::lonnet::logthis('    '.$top_sum.'/'.$top_max.
+    #                         ' - '.$bottom_sum.'/'.$bottom_max);
+    return $deg_of_disc;
 }
-=cut
 
-sub BuildStatisticsTable {
-    my ($cache,$discriminantFactor,$list,$headings,$students,$r,%color)=@_;
+###############################################
+###############################################
 
-#6666666
-#    my $file="/home/httpd/perl/tmp/183d.txt";
-#    open(OUT, ">$file");
-#6666666
-##     &Apache::lonstatistics::Create_PrgWin($r);
-##777777
-##    my (%Activity) = &LoadActivityLog();
-##    $r->print('<script>popwin.document.popremain.remaining.value="'.
-##              'Loading Discussion...";</script>');
-##    my ($doDiffFile) = &LoadDoDiffFile();
-
-    my $p_count = 0;
-    my $nIndex = 0;
-    my $dummy;
-    my $p_val;
-    my $ResId;
-    my %GraphDat;
-    my $NoElements = scalar @$list;
-
-    foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
-        if($cache->{'ProblemStatisticsMap'} ne 'All Maps'  &&
-           $cache->{'ProblemStatisticsMap'} ne $cache->{$sequence.':title'}) {
-            next;
-        }
+=pod 
 
-	&CreateProblemStatisticsTableHeading($cache->{'DisplayFormat'},
-                                             $cache->{$sequence.':source'}, 
-                                             $cache->{$sequence.':title'},
-                                             $headings,$r);
-
-##777777
-##    $Str .= &Classify($discriminantFactor, $students);
-
-
-	my ($Hid,$pr)=split(/\:/,$mapsort{$_});
-	my @lpr=split(/\&/,$pr);
-	for (my $i=1; $i<=$#lpr; $i++) {
-	    my %storestats=();
-	    my ($PrOrd,$Prob,$Tries,$Wrongs,$Code,$Disc)=split(/\&/,$list->[$nIndex]);
-	    my $Temp = $Prob;
-	    my $MxTries = 0;
-	    my $TotalTries = 0;
-	    my $YES = 0;
-	    my $Incorrect = 0;
-	    my $Override = 0;
-	    my $StdNo = 0;
-	    my $DiscNo=0;
-	    my @StdLst;
-	    while ( $PrOrd == $lpr[$i] ) 
-	    {
-		$nIndex++;
-		$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' ) { $StdNo--; }
-		($PrOrd,$Prob,$Tries,$Wrongs,$Code,$Disc)=split(/\&/,$list->[$nIndex]);
-	    }	
-
-	    $p_count++;
-	    my $Dummy;
-	    ($ResId,$Dummy)=split(/\*/,$Temp);
-
-	    $Temp = '<a href="'.$cache->{'src_'.$ResId}.
-                '" target="_blank">'.$cache->{'title_'.$ResId}.$Dummy.'</a>';
-
-	    my $res = &Apache::lonnet::declutter($cache->{'src_'.$ResId});
-	    my $urlres=$res;
-
-	    $ResId=~/(\d+)\.(\d+)/;
-	    my $Map = &Apache::lonnet::declutter( $cache->{'map_id_'.$1} );
-	    $urlres=$Map;
- 
-	    $res = '<a href="'.$cache->{'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*$StdDev;
-	    }
-
-#--------------------- Compute the Discrimination Factors
-            my ($Up1,$Up2)=split(/\:/,':');#jason$DisUp->{$lpr[$i]});
-	    my ($Lw1,$Lw2)=split(/\:/,':');#jason$DisLow->{$lpr[$i]});
-	    my $Dis1 = $Up1 - $Lw1;
-	    my $Dis2 = $Up2 - $Lw2;
-	    my $_D1 = sprintf("%.2f", $Dis1);
-	    my $_D2 = sprintf("%.2f", $Dis2);
-
-#-----------------  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 );
-	    my $join = $lpr[$i].'&'.$Temp.'&'.$StdNo.'&'.
-                       $TotalTries.'&'.$MxTries.'&'.$Avg.'&'.
-                       $YES.'&'.$Override.'&'.$Wrng.'&'.$DoD.'&'.
-		       $SD.'&'.$Sk.'&'.$_D1.'&'.$_D2.'&'.
-                       $DiscNo.'&'.$Prob;
-##8888	    $CachData{($p_count-1)}=$join;
-
-#6666666
-#	    $r->print('<br>'.$out.'&'.$DoD);
-#            print (OUT $out.'@'.$DoD.'&');
-#6666666
-
-	    $urlres=~/^(\w+)\/(\w+)/;
-	    if ($StdNo) { 
-		&Apache::lonnet::put('resevaldata',\%storestats,$1,$2); 
-	    }
-#-------------------------------- Row of statistical table
-            &TableRow($cache,$join,$i,($p_count-1),$r,\%color,\%GraphDat);
-	}
-	&CloseTable($cache,$r);
-    }
-    &Close_PrgWin();
-#666666
-#    close( OUT );
-#666666
-}
+=item ProblemStatisticsLegend
 
-=pod
-sub Cache_Statistics {
-    my ($cache,$color)=@_;
-    my @list = ();
-    my $Useful;
-    my $UnUseful;
-#    $r->print('<input type="hidden" name="show" value="excel" />'."\n"); 
-    my %myHeader = reverse( %Header );
-    $Pos = $myHeader{$ENV{'form.sort'}};
-    if ($Pos > 0) {$Pos++;}
-    my $p_count = 0;
-    foreach my $key( keys %CachData) { 
-	my @Temp=split(/\&/,$CachData{$key});
-	if ( $Pos == 0 ) {
-	    ($UnUseful,$Useful)=split(/\>/,$Temp[$Pos]);
-	}
-	else {
-	    $Useful = $Temp[$Pos];
-	}   
-	$list[$p_count]=$Useful.'@'.$CachData{$key};
-        $p_count++;
-    }
-
-    @list = sort MySort (@list);
-
-    my $nIndex=0;
-
-    if ( $Pos == 0 ) {
-	foreach (sort keys %mapsort) {
-	    my ($Hid,$pr)=split(/\:/,$mapsort{$_});
-	    &CreateProblemStatisticsTableHeading($cache,1,$Hid);
-	    my @lpr=split(/\&/,$pr);
-	    for (my $i=1; $i<=$#lpr; $i++) {
-		my($Pre, $Post) = split(/\@/,$list[$nIndex]); 
-		#$r->print('<br>'.$Pre.'---'.$Post);
-		&TableRow($cache,$Post,$i,$nIndex,\%color,\%GraphDat);
-		$nIndex++;
-	    }
-	    &CloseTable($cache);
-	}
-    }
-    else {
-	&CreateProblemStatisticsTableHeading($cache,0);
-	for ( my $nIndex = 0; $nIndex < $p_count; $nIndex++ ) {
-	    my($Pre, $Post) = split(/\@/,$list[$nIndex]); 
-	    &TableRow($cache,$Post,$nIndex,$nIndex,\%color,\%GraphDat);
-	} 
-	&CloseTable($cache);
-    }
-}
-=cut 
-
-sub TableRow {
-    my ($cache,$Str,$Idx,$RealIdx,$r,$color,$GraphDat)=@_;
-    my($PrOrd,$Temp,$StdNo,$TotalTries,$MxTries,$Avg,$YES,$Override,
-       $Wrng,$DoD,$SD,$Sk,$_D1,$_D2,$DiscNo,$Prob)=split(/\&/,$Str);	
-    if ($ENV{'form.showcsv'}) {
-        my ($ResId,$Dummy)=split(/\*/,$Prob);
-        my $Ptr =  "\n".'<br>'.
-               "\n".'"'.($RealIdx+1).'",'.
-               "\n".'"'.$cache->{'title_'.$ResId}.$Dummy.'",'.
-               "\n".'"'.$cache->{'src_'.$ResId}.'",'.
-               "\n".'"'.$StdNo.'",'.
-               "\n".'"'.$TotalTries.'",'.
-               "\n".'"'.$MxTries.'",'.
-               "\n".'"'.$Avg.'",'.
-               "\n".'"'.$YES.'",'.
-               "\n".'"'.$Override.'",'.
-               "\n".'"'.$Wrng.'",'.
-               "\n".'"'.$DoD.'",'.
-               "\n".'"'.$SD.'",'.
-               "\n".'"'.$Sk.'",'.
-               "\n".'"'.$_D1.'",'.
-	       "\n".'"'.$_D2.'"'.
-	       "\n".'"'.$DiscNo.'"';
-
-        $r->print("\n".$Ptr);
-    }
-    else{
-        my $Ptr =  "\n".'<tr>'.
-               "\n".'<td>'.($RealIdx+1).'</td>'.
-          #     "\n".'<td>'.$PrOrd.$Temp.'</td>'.
-               "\n".'<td>'.$Temp.'</td>'.
-               "\n".'<td bgcolor='.$color->{"yellow"}.'> '.$StdNo.'</td>'.
-               "\n".'<td bgcolor='.$color->{"yellow"}.'>'.$TotalTries.'</td>'.
-               "\n".'<td bgcolor='.$color->{"yellow"}.'>'.$MxTries.'</td>'.
-               "\n".'<td bgcolor='.$color->{"gb"}.'>'.$Avg.'</td>'.
-               "\n".'<td bgcolor='.$color->{"gb"}.'> '.$YES.'</td>'.
-               "\n".'<td bgcolor='.$color->{"gb"}.'> '.$Override.'</td>'.
-               "\n".'<td bgcolor='.$color->{"red"}.'> '.$Wrng.'</td>'.
-               "\n".'<td bgcolor='.$color->{"red"}.'> '.$DoD.'</td>'.
-               "\n".'<td bgcolor='.$color->{"green"}.'> '.$SD.'</td>'.
-               "\n".'<td bgcolor='.$color->{"green"}.'> '.$Sk.'</td>'.
-               "\n".'<td bgcolor='.$color->{"purple"}.'> '.$_D1.'</td>'.
-	       "\n".'<td bgcolor='.$color->{"purple"}.'> '.$_D2.'</td>'.
-               "\n".'<td bgcolor='.$color->{"yellow"}.'> '.$DiscNo.'</td>';
-        $r->print("\n".$Ptr.'</tr>' );
-    }
-    $GraphDat->{$RealIdx}=$DoD.':'.$Wrng;
-}
-
-sub StatusOptions {
-    my ($cache)=@_;
-
-    my $Status = $cache->{'Status'};
-    my $OpSel1 = '';
-    my $OpSel2 = '';
-    my $OpSel3 = '';
-
-    if($Status eq 'Any')         { $OpSel3 = ' selected'; }
-    elsif($Status eq 'Expired' ) { $OpSel2 = ' selected'; }
-    else                         { $OpSel1 = ' selected'; }
-
-    my $Ptr = '';
-    $Ptr .= '<tr><td align="right"><b>Student Status:</b></td>'."\n";
-    $Ptr .= '<td align="left"><select name="Status">';
-    $Ptr .= '<option'.$OpSel1.'>Active</option>'."\n";
-    $Ptr .= '<option'.$OpSel2.'>Expired</option>'."\n";
-    $Ptr .= '<option'.$OpSel3.'>Any</option>'."\n";
-    $Ptr .= '</select></td></tr>'."\n";
-
-    return $Ptr;
-}
+=over 4
 
-sub AscendOrderOptions {
-    my ($order)=@_;
+=item #Stdnts
+Total number of students attempted the problem.
 
-    my $OpSel1 = '';
-    my $OpSel2 = '';
+=item Tries
+Total number of tries for solving the problem.
 
-    if($order eq 'Ascending') {
-        $OpSel1 = ' selected';
-    } else {
-        $OpSel2 = ' selected';
-    }
+=item Max Tries
+Largest number of tries for solving the problem by a student.
+
+=item Mean
+Average number of tries. [ Tries / #Stdnts ]
+
+=item #YES
+Number of students solved the problem correctly.
+
+=item #yes
+Number of students solved the problem by override.
+
+=item %Wrong
+Percentage of students who tried to solve the problem 
+but is still incorrect. [ 100*((#Stdnts-(#YES+#yes))/#Stdnts) ]
+
+=item DoDiff
+Degree of Difficulty of the problem.  
+[ 1 - ((#YES+#yes) / Tries) ]
+
+=item S.D.
+Standard Deviation of the tries.  
+[ sqrt(sum((Xi - Mean)^2)) / (#Stdnts-1) 
+where Xi denotes every student\'s tries ]
+
+=item Skew.
+Skewness of the students tries.
+[(sqrt( sum((Xi - Mean)^3) / #Stdnts)) / (S.D.^3)]
 
-    my $Ptr = '';
-    $Ptr .= '<tr><td align="right"><b>Sorting Type:</b></td>'."\n";
-    $Ptr .= '<td align="left"><select name="Ascend">'."\n";
-    $Ptr .= '<option'.$OpSel1.'>Ascending</option>'."\n".
-	    '<option'.$OpSel2.'>Descending</option>'."\n";
-    $Ptr .= '</select></td></tr>'."\n";
-
-    return $Ptr;
-}
-
-sub ProblemStatisticsButtons {
-    my ($displayFormat)=@_;
-
-    my $Ptr = '<tr><td></td><td align="left">';
-    $Ptr .= '<input type=submit name="ProblemStatisticsRecalculate" ';
-    $Ptr .= 'value="Recalculate Statistics"/>'."\n";
-    $Ptr .= '&nbsp;&nbsp;&nbsp;';
-    $Ptr .= '<input type="submit" name="DoDiffGraph" ';
-    $Ptr .= 'value="DoDiff Graph" />'."\n";
-    $Ptr .= '&nbsp;&nbsp;&nbsp;';
-    $Ptr .= '<input type="submit" name="PercentWrongGraph" ';
-    $Ptr .= 'value="%Wrong Graph" />'."\n";
-    $Ptr .= '&nbsp;&nbsp;&nbsp;';
-    $Ptr .= '<input type="submit" name="DisplayCSVFormat" ';
-    if($displayFormat eq 'Display CSV Format') {
-        $Ptr .= 'value="Display CSV Format" />'."\n";
+=item Dis.F.
+Discrimination Factor: A Standard for evaluating the 
+problem according to a Criterion<br>
+
+=item [Criterion to group students into %27 Upper Students - 
+and %27 Lower Students]
+1st Criterion for Sorting the Students: 
+Sum of Partial Credit Awarded / Total Number of Tries
+2nd Criterion for Sorting the Students: 
+Total number of Correct Answers / Total Number of Tries
+
+=item Disc.
+Number of Students had at least one discussion.
+
+=back
+
+=cut
+
+
+############################################################
+############################################################
+##
+##  How this all works:
+##     Statistics are computed by calling &get_statistics with the sequence,
+##     resource, and part id to run statistics on.  At various places within
+##     the loops which compute the statistics, as well as before and after 
+##     the entire process, subroutines can be called.  The subroutines are
+##     registered to the following hooks:
+##
+##         hook          subroutine inputs
+##     ----------------------------------------------------------
+##         pre           $r,$count
+##         pre_seq       $r,$count,$seq
+##         pre_res       $r,$count,$seq,$res
+##         calc          $r,$count,$seq,$res,$data
+##         post_res      $r,$count,$seq,$res
+##         post_seq      $r,$count,$seq
+##         post          $r,$count
+##
+##         abort         $r
+##
+##     subroutines will be called in the order in which they are registered.
+##   
+############################################################
+############################################################
+{
+
+my %hooks;
+my $aborted = 0;
+
+sub abort_computation {
+    $aborted = 1;
+}
+
+sub clear_hooks {
+    $aborted = 0;
+    undef(%hooks);
+}
+
+sub register_hook {
+    my ($hookname,$subref)=@_;
+    if ($hookname !~ /^(pre|pre_seq|pre_res|post|post_seq|post_res|calc)$/){
+        return;
+    }
+    if (ref($subref) ne 'CODE') {
+        &Apache::lonnet::logthis('attempt to register hook to non-code: '.
+                                 $hookname,' = '.$subref);
     } else {
-        $Ptr .= 'value="Display Table Format" />'."\n";
+        if (exists($hooks{$hookname})) {
+            push(@{$hooks{$hookname}},$subref);
+        } else {
+            $hooks{$hookname} = [$subref];
+        }
     }
-    $Ptr .= '</td></tr>';
+    return;
+}
 
-    return $Ptr;
+sub run_hooks {
+    my $context = shift();
+    foreach my $hook (@{$hooks{$context}}) { 
+        if ($aborted && $context ne 'abort') {
+            last;
+        }
+        my $retvalue = $hook->(@_);
+        if (defined($retvalue) && $retvalue eq '0') {
+            $aborted = 1 if (! $aborted);
+        }
+    }
 }
 
-sub ProblemStatisticsLegend {
-    my $Ptr = '';
-    $Ptr = '<table border="0">';
-    $Ptr .= '<tr><td>';
-    $Ptr .= '<b>#Stdnts</b>:</td>';
-    $Ptr .= '<td>Total Number of Students opened the problem.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Tries</b>:</td>';
-    $Ptr .= '<td>Total Number of Tries for solving the problem.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Mod</b>:</td>';
-    $Ptr .= '<td>Maximunm Number of Tries for solving the problem.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Mean</b>:</td>';
-    $Ptr .= '<td>Average Number of the tries. [ Tries / #Stdnts ]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>#YES</b>:</td>';
-    $Ptr .= '<td>Number of students solved the problem correctly.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>#yes</b>:</td>';
-    $Ptr .= '<td>Number of students solved the problem by override.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>%Wrng</b>:</td>';
-    $Ptr .= '<td>Percentage of students tried to solve the problem ';
-    $Ptr .= 'but still incorrect. [ 100*((#Stdnts-(#YES+#yes))/#Stdnts) ]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>DoDiff</b>:</td>';
-    $Ptr .= '<td>Degree of Difficulty of the problem.  ';
-    $Ptr .= '[ 1 - ((#YES+#yes) / Tries) ]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>S.D.</b>:</td>';
-    $Ptr .= '<td>Standard Deviation of the tries.  ';
-    $Ptr .= '[ sqrt(sum((Xi - Mean)^2)) / (#Stdnts-1) ';
-    $Ptr .= 'where Xi denotes every student\'s tries ]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Skew.</b>:</td>';
-    $Ptr .= '<td>Skewness of the students tries.';
-    $Ptr .= '[(sqrt( sum((Xi - Mean)^3) / #Stdnts)) / (S.D.^3)]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Dis.F.</b>:</td>';
-    $Ptr .= '<td>Discrimination Factor: A Standard for evaluating the ';
-    $Ptr .= 'problem according to a Criterion<br>';
-    $Ptr .= '<b>[Applied Criterion in %27 Upper Students - ';
-    $Ptr .= 'Applied the same Criterion in %27 Lower Students]</b><br>';
-    $Ptr .= '<b>1st Criterion</b> for Sorting the Students: ';
-    $Ptr .= '<b>Sum of Partial Credit Awarded / Total Number of Tries</b><br>';
-    $Ptr .= '<b>2nd Criterion</b> for Sorting the Students: ';
-    $Ptr .= '<b>Total number of Correct Answers / Total Number of Tries</b>';
-    $Ptr .= '</td></tr>';
-    $Ptr .= '<tr><td><b>Disc.</b></td>';
-    $Ptr .= '<td>Number of Students had at least one discussion.';
-    $Ptr .= '</td></tr></table>';
-
-    return $Ptr;
-}
-
-#---- END Problem Statistics Web Page ----------------------------------------
-
-#---- Problem Statistics Graph Web Page --------------------------------------
-
-# ------------------------------------------- Prepare data for Graphical chart
-
-sub GetGraphData {
-    my ($ylab,$r,%GraphDat)=@_;
-    my $Col;
-    my $data='';
+sub run_statistics {
+    my ($r) = @_;
     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 ( $ylab eq 'DoDiff Graph' ) {
-		$ylab = 'Degree-of-Difficulty';
-		$Col = 0;
-	    }
-	    else {
-		$ylab = '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++;
-	    }
-	    if ( $Max > 1 ) { 
-		$Max += (10 - $Max % 10);
-		$Max = int($Max);
-	    }
-	    else { $Max = 1; }
-            untie(%GraphDat);
-	    my $Course = $ENV{'course.'.$cid.'.description'};
-	    $Course =~ s/\ /"_"/eg;
-	    my $GData=$Course.'&'.'Problems'.'&'.$ylab.'&'.$Max.'&'.$count.'&'.$data;
-	}
-	else {
-	    $r->print("Unable to tie hash to db file");
-	}
+    &run_hooks('pre',$r,$count);
+    foreach my $seq (&Apache::lonstatistics::Sequences_with_Assess()) {
+        last if ($aborted);
+        next if ($seq->{'num_assess'}<1);
+        &run_hooks('pre_seq',$r,$count,$seq);
+        foreach my $res (@{$seq->{'contents'}}) {
+            last if ($aborted);
+            next if ($res->{'type'} ne 'assessment');
+            &run_hooks('pre_res',$r,$count,$seq,$res);            
+            foreach my $part (@{$res->{'parts'}}) {
+                last if ($aborted);
+                #
+                # This is where all the work happens
+                my $data = &get_statistics($seq,$res,$part,++$count);
+                &run_hooks('calc',$r,$count,$seq,$res,$part,$data); 
+            }
+            &run_hooks('post_res',$r,$count,$seq,$res);
+        }
+        &run_hooks('post_seq',$r,$count,$seq);
     }
+    if ($aborted) {
+        &run_hooks('abort',$r);
+    } else {
+        &run_hooks('post',$r,$count);
+    }
+    return;
 }
+
+} # End of %hooks scope
+
+############################################################
+############################################################
+
 1;
 __END__