--- loncom/interface/statistics/lonproblemstatistics.pm	2002/08/13 00:37:18	1.19
+++ loncom/interface/statistics/lonproblemstatistics.pm	2003/06/16 15:54:58	1.54
@@ -1,7 +1,6 @@
 # The LearningOnline Network with CAPA
-# (Publication Handler
 #
-# $Id: lonproblemstatistics.pm,v 1.19 2002/08/13 00:37:18 stredwic Exp $
+# $Id: lonproblemstatistics.pm,v 1.54 2003/06/16 15:54:58 matthew Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -26,356 +25,882 @@
 # 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
-# 5/12,5/14,5/15,5/19,5/26,7/16,7/25,7/29,8/5  Behrouz Minaei
 #
-###
+###############################################
+###############################################
 
-package Apache::lonproblemstatistics; 
+=pod
+
+=head1 NAME
+
+lonproblemstatistics
+
+=head1 SYNOPSIS
+
+Routines to present problem statistics to instructors via tables,
+Excel files, and plots.
+
+=over 4
+
+=cut
+
+###############################################
+###############################################
+
+package Apache::lonproblemstatistics;
 
 use strict;
 use Apache::lonnet();
 use Apache::lonhtmlcommon;
 use Apache::loncoursedata;
-use GDBM_File;
+use Apache::lonstatistics;
+use Spreadsheet::WriteExcel;
 
-my $jr;
+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   => '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   => 'deg_of_diff',
+             title  => 'DoDiff',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%5.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Degree of Difficulty' },
+           { name   => 'num_solved',
+             title  => '#YES',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Number of Students able to Solve' },
+           { name   => 'num_override',
+             title  => '#yes',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Number of Students given Override' },
+           { name   => 'per_wrong',
+             title  => '%Wrng',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%4.1f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Percent Wrong' },
+);
+
+###############################################
+###############################################
 
-sub BuildProblemStatisticsPage {
-    my ($cacheDB, $students, $courseID, $c, $r)=@_;
-    my %cache;
+=pod 
 
-    $jr = $r;
+=item &CreateInterface()
 
-    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
-        return '<html><body>Unable to tie database.</body></html>';
-    }
+Create the main intereface for the statistics page.  Allows the user to
+select sections, maps, and output.
 
-    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',
-                                               'Statistics');
-    $Ptr .= '</td></tr>'."\n";
-    $Ptr .= '<tr><td align="right"><b>Sorting Type:</b></td>'."\n";
-    $Ptr .= '<td align="left">'."\n";
-    $Ptr .= &Apache::lonhtmlcommon::AscendOrderOptions(
-                                            $cache{'ProblemStatisticsAscend'}, 
-                                            'ProblemStatistics',
-                                            'Statistics');
-    $Ptr .= '</td></tr>'."\n";
-    $Ptr .= &ProblemStatisticsButtons($cache{'DisplayFormat'});
-    $Ptr .= '</table>';
-    $Ptr .= &ProblemStatisticsLegend();
-    $r->print($Ptr);
-    $r->rflush();
+=cut
 
-    untie(%cache);
+###############################################
+###############################################
+sub CreateInterface {
+    my $Str = '';
+    $Str .= '<table cellspacing="5">'."\n";
+    $Str .= '<tr>';
+    $Str .= '<td align="center"><b>Sections</b></td>';
+    $Str .= '<td align="center"><b>Enrollment Status</b></td>';
+    $Str .= '<td align="center"><b>Sequences and Folders</b></td>';
+    $Str .= '<td align="center"><b>Output</b></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><td>'."\n";
+    $Str .= &CreateAndParseOutputSelector();
+    $Str .= '</td></tr>'."\n";
+    $Str .= '</table>'."\n";
+    $Str .= '<input type="submit" value="Generate Statistics" />';
+    $Str .= '&nbsp;'x5;
+    $Str .= '<input type="submit" name="ClearCache" value="Clear Caches" />';
+    $Str .= '&nbsp;'x5;
+    return $Str;
+}
 
-    &Apache::loncoursedata::DownloadStudentCourseDataSeparate($students,'true',
-                                                              $cacheDB,'true', 
-                                                              'true',$courseID,
-                                                              $r, $c);
-    if($c->aborted()) { return; }
-
-    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
-        return '<html><body>Unable to tie database.</body></html>';
-    }
-
-    my @Header = ("Homework Sets Order","#Stdnts","Tries","Mod",
-                  "Mean","#YES","#yes","%Wrng","DoDiff",
-                  "S.D.","Skew.","D.F.1st","D.F.2nd","Disc.");
-    my $color=&setbgcolor(0);
-
-#    my %Discuss=&Apache::loncoursedata::LoadDiscussion($courseID);
-#    my ($upper, $lower) = &Discriminant(\%discriminant,$r);
-    my ($problemData) = &ExtractStudentData(\%cache, $students);
-    &CalculateStatistics($problemData);
-    &SortProblems($problemData, $cache{'ProblemStatisticsSort'},
-                  $cache{'ProblemStatisticsAscend'});
-    #$TempCache=
-    &BuildStatisticsTable(\%cache, $cache{'DisplayFormat'},
-                          $problemData, \@Header, $r, $color);
-    untie(%cache);
-
-#    foreach (keys %$TempCache) {
-#        last if ($c->aborted());
-#        if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT(),0640)) {
-#	    $cache{$_}=$TempCache->{$_};
-#            untie(%cache);
-#        }
-#    }
+#######################################################
+#######################################################
 
-#    if($c->aborted()) { return; }
-#    untie(%cache);
+=pod
 
-    return;
-}
+=item &CreateAndParseOutputSelector()
 
+Construct a selection list of options for output and parse output selections.
+The current output selected is indicated by the values of the two package
+variables $output_mode and $show.  @OutputOptions holds the descriptions of
+the output options and the values for $output_mode and $show.
 
-#---- Problem Statistics Web Page ---------------------------------------
+Based on code from lonstudentassessment.pm.
 
-sub CreateProblemStatisticsTableHeading {
-    my ($headings,$r)=@_;
+=cut
 
-    my $Str='';
-    $Str .= '<tr>'."\n";
-    $Str .= '<th bgcolor="#ffffe6">P#</th>'."\n";
-    foreach(@$headings) {
-	$Str .= '<th bgcolor="#ffffe6">'.'<a href="/adm/statistics?reportSelected=';
-        $Str .= &Apache::lonnet::escape('Problem Statistics');
-        $Str .= '&ProblemStatisticsSort=';
-        $Str .= &Apache::lonnet::escape($_).'">'.$_.'</a>&nbsp</th>'."\n";
+#######################################################
+#######################################################
+my $output_mode;
+my $show;
+
+my @OutputOptions = 
+    (
+     { name  => 'problem statistics grouped by sequence',
+       value => 'HTML problem statistics grouped',
+       description => 'Output statistics for the problem parts.',
+       mode => 'html',
+       show => 'grouped',
+     },
+     { name  => 'problem statistics ungrouped',
+       value => 'HTML problem statistics ungrouped',
+       description => 'Output statistics for the problem parts.',
+       mode => 'html',
+       show => 'ungrouped',
+     },
+     { name  => 'problem statistics, Excel',
+       value => 'Excel problem statistics',
+       description => 'Output statistics for the problem parts '.
+           'in an Excel workbook',
+       mode => 'excel',
+       show => 'all',
+     },
+     );
+
+sub OutputDescriptions {
+    my $Str = '';
+    $Str .= "<h2>Output Modes</h2>\n";
+    $Str .= "<dl>\n";
+    foreach my $outputmode (@OutputOptions) {
+	$Str .="    <dt>".$outputmode->{'name'}."</dt>\n";
+	$Str .="        <dd>".$outputmode->{'description'}."</dd>\n";
     }
-    $Str .= "\n".'</tr>'."\n";    
+    $Str .= "</dl>\n";
+    return $Str;
+}
 
+sub CreateAndParseOutputSelector {
+    my $Str = '';
+    my $elementname = 'statsoutputmode';
+    #
+    # Format for output options is 'mode, restrictions';
+    my $selected = 'HTML problem statistics grouped';
+    if (exists($ENV{'form.'.$elementname})) {
+        if (ref($ENV{'form.'.$elementname} eq 'ARRAY')) {
+            $selected = $ENV{'form.'.$elementname}->[0];
+        } else {
+            $selected = $ENV{'form.'.$elementname};
+        }
+    }
+    #
+    # Set package variables describing output mode
+    $output_mode = 'html';
+    $show        = 'all';
+    foreach my $option (@OutputOptions) {
+        next if ($option->{'value'} ne $selected);
+        $output_mode = $option->{'mode'};
+        $show        = $option->{'show'};
+    }
+    #
+    # Build the form element
+    $Str = qq/<select size="5" name="$elementname">/;
+    foreach my $option (@OutputOptions) {
+        if (exists($option->{'special'}) && 
+            $option->{'special'} =~ /do not show/) {
+            next;
+        }
+        $Str .= "\n".'    <option value="'.$option->{'value'}.'"';
+        $Str .= " selected " if ($option->{'value'} eq $selected);
+        $Str .= ">".$option->{'name'}."<\/option>";
+    }
+    $Str .= "\n</select>";
     return $Str;
 }
 
-sub BuildStatisticsTable {
-    my ($cache,$displayFormat,$data,$headings,$r,$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();
-
-##777777
-##    $Str .= &Classify($discriminantFactor, $students);
-
-    my %TempCache;
-    my $problems = $data->{'problemList'};
-    if($displayFormat ne 'Display CSV Format') {
-        $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n");
-        $r->print('<table border="0" cellpadding="3">'."\n");
-        $r->print(&CreateProblemStatisticsTableHeading($headings, $r));
+=pod 
+
+=item &Gather_Student_Data()
+
+Ensures all student data is up to date.
+
+=cut
+
+###############################################
+###############################################
+sub Gather_Student_Data {
+    my ($r) = @_;
+    my $c = $r->connection();
+    #
+    my @Sequences = &Apache::lonstatistics::Sequences_with_Assess();
+    #
+    my @Students = @Apache::lonstatistics::Students;
+    #
+    # Open the progress window
+    my %prog_state=&Apache::lonhtmlcommon::Create_PrgWin
+        ($r,'Statistics Compilation Status',
+         'Statistics Compilation Progress', scalar(@Students));
+    #
+    while (my $student = shift @Students) {
+        return if ($c->aborted());
+        my ($status,undef) = &Apache::loncoursedata::ensure_current_data
+            ($student->{'username'},$student->{'domain'},
+             $ENV{'request.course.id'});
+        &Apache::lonhtmlcommon::Increment_PrgWin($r,\%prog_state,
+                                                 'last student');
+    }
+    &Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
+    $r->rflush();
+}
+
+###############################################
+###############################################
+
+=pod 
+
+=item &BuildProblemStatisticsPage()
+
+Main interface to problem statistics.
+
+=cut
+
+###############################################
+###############################################
+sub BuildProblemStatisticsPage {
+    my ($r,$c)=@_;
+    #
+    $output_mode = 'html';
+    $show = 'grouped';
+    #
+    $r->print(&CreateInterface());
+    $r->print('<input type="hidden" name="statsfirstcall" value="no" />');
+    $r->print('<input type="hidden" name="sortby" value="'.$ENV{'form.sortby'}.
+              '" />');
+    $r->print('<input type="hidden" name="plot" value="" />');
+    if (! exists($ENV{'form.statsfirstcall'})) {
+        return;
+    }
+    #
+    &Gather_Student_Data($r);
+    #
+    #
+    if ($output_mode eq 'html') {
+        $r->print("<h2>".
+                  $ENV{'course.'.$ENV{'request.course.id'}.'.description'}.
+                  "</h2>\n");
+        $r->print("<h3>".localtime(time)."</h3>");
+        $r->rflush();
+        if ($show eq 'grouped') {
+            &output_html_grouped_by_sequence($r);
+        } elsif ($show eq 'ungrouped') {
+            &output_html_ungrouped($r);
+        }
+    } elsif ($output_mode eq 'excel') {
+        $r->print("<h2>Preparing Excel Spreadsheet</h2>");
+        &output_excel($r);
     } else {
-        $r->print('<br>');
+        $r->print("<h1>Not implemented</h1>");
     }
+    return;
+}
+
+###############################################
+###############################################
 
-    my $count = 1;
-    foreach(@$problems) {
-        my ($sequence,$problem,$part)=split(':', $_);
-#        my $problemRef = '<a href="'.$cache->{$problem.':source'}.
-#                '" target="_blank">'.$cache->{$problem.':title'}.'</a>';
-
-        my $ref = $cache->{$problem.':title'};
-        my $title = $cache->{$problem.':title'};
-        my $source = 'source';
-        my $tableData = join('&', $ref, $title, $source,
-                         $data->{$_.':studentCount'},
-                         $data->{$_.':totalTries'},
-                         $data->{$_.':maxTries'},
-                         sprintf("%.2f", $data->{$_.':mean'}),
-                         $data->{$_.':correct'},
-                         $data->{$_.':correctByOverride'},
-                         sprintf("%.1f", $data->{$_.':percentWrong'}),
-                         sprintf("%.2f", $data->{$_.':degreeOfDifficulty'}),
-                         sprintf("%.1f", $data->{$_.':standardDeviation'}),
-                         sprintf("%.1f", $data->{$_.':skewness'}),
-                         sprintf("%.2f", $data->{$_.':discriminationFactor1'}),
-                         sprintf("%.2f", $data->{$_.':discriminationFactor2'}),
-                         0); # 0 is for discussion, need to figure out
-#        $TempCache{'CacheTable:'.$_}=$join;
-
-#6666666
-#	    $r->print('<br>'.$out.'&'.$DoD);
-#            print (OUT $out.'@'.$DoD.'&');
-#6666666
-
-#check with Gerd
-#        $urlres=~/^(\w+)\/(\w+)/;
-#        if ($StdNo) {
-#            &Apache::lonnet::put('nohist_resevaldata',\%storestats,
-#                                 $1,$2);
-#        }
-#-------------------------------- Row of statistical table
-        &TableRow($displayFormat,$tableData,$count,$r,$color);
-#        $GraphDat->{'GraphGif:'.($count-1)}=$DoD.':'.$Wrng;
-        $count++;
-    }
-#    $TempCache{'ProblemCount'}=$count;
-    if($cache->{'DisplayFormat'} ne 'Display CSV Format') {
-        $r->print('</table>'."\n");
-    }
-    $r->print('</td></tr></table>');
-#6666666
-#    close( OUT );
-#666666
-    return \%TempCache;
+=pod 
+
+=item &output_html_grouped_by_sequence()
+
+Presents the statistics data as an html table organized by the order
+the assessments appear in the course.
+
+=cut
+
+###############################################
+###############################################
+sub output_html_grouped_by_sequence {
+    my ($r) = @_;
+    my $problem_num = 0;
+    #$r->print(&ProblemStatisticsLegend());
+    foreach my $sequence (&Apache::lonstatistics::Sequences_with_Assess()) {
+        next if ($sequence->{'num_assess'}<1);
+        $r->print("<h3>".$sequence->{'title'}."</h3>");
+        $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n");
+        $r->print('<table border="0" cellpadding="3">'."\n");
+        $r->print('<tr bgcolor="#FFFFE6">');
+        my $Str = &statistics_table_header('no container no plots');
+        $r->print('<tr bgcolor="#FFFFE6">'.$Str."</tr>\n");
+        foreach my $resource (@{$sequence->{'contents'}}) {
+            next if ($resource->{'type'} ne 'assessment');
+            foreach my $part (@{$resource->{'parts'}}) {
+                $problem_num++;
+                my $data = &get_statistics($sequence,$resource,$part,
+                                           $problem_num);
+                my $option = '';
+                $r->print('<tr>'.&statistics_html_table_data($data,
+                                                             'no container').
+                          "</tr>\n");
+            }
+        }
+        $r->print("</table>\n");
+        $r->print("</td></tr></table>\n");
+        $r->rflush();
+    }
+    #
+    return;
 }
 
-=pod
-sub CacheStatisticsTable {
-    my ($state,$cache,$headings,$r,$color)=@_;
-    my @list = (); 
-    my %TempCache;
-    my %myHeader = reverse( %$headings );
-    my $pos = $myHeader{$state};
-    if ($pos > 0) {$pos++;}
-    my $p_count = $cache->{'ProblemCount'};
-
-    for ( my $k=0; $k<$p_count;$k++) {
-	my $key=$cache->{'CacheTable:'.$k};
-	my @Temp=split(/\&/,$key);
-	$list[$k]=$Temp[$pos].'+'.$key;
+###############################################
+###############################################
+
+=pod 
+
+=item &output_html_ungrouped()
+
+Presents the statistics data in a single html table which can be sorted by
+different columns.
+
+=cut
+
+###############################################
+###############################################
+sub output_html_ungrouped {
+    my ($r,$option) = @_;
+    #
+    if (exists($ENV{'form.plot'}) && $ENV{'form.plot'} ne '') {
+        &plot_statistics($r,$ENV{'form.plot'});
+    }
+    #
+    my $problem_num = 0;
+    my $show_container = 0;
+    my $show_part = 0;
+    #$r->print(&ProblemStatisticsLegend());
+    my $sortby = undef;
+    foreach my $field (@Fields) {
+        if ($ENV{'form.sortby'} eq $field->{'name'}) {
+            $sortby = $field->{'name'};
+        }
     }
-    
-    if ($pos>0) {
-        @list = sort OrderedSort (@list);
+    if (! defined($sortby) || $sortby eq '' || $sortby eq 'problem_num') {
+        $sortby = 'container';
+    }
+    # If there is more than one sequence, list their titles
+    my @Sequences = &Apache::lonstatistics::Sequences_with_Assess();
+    if (@Sequences < 1) {
+        $option .= ' no container';
+    }
+    #
+    # Compile the data
+    my @Statsarray;
+    foreach my $sequence (@Sequences) {
+        next if ($sequence->{'num_assess'}<1);
+        foreach my $resource (@{$sequence->{'contents'}}) {
+            next if ($resource->{'type'} ne 'assessment');
+            foreach my $part (@{$resource->{'parts'}}) {
+                $problem_num++;
+                my $data = &get_statistics($sequence,$resource,$part,
+                                           $problem_num);
+                $show_part = 1 if ($part ne '0');
+                #
+                push (@Statsarray,$data);
+            }
+        }
+    }
+    #
+    # Sort the data
+    my @OutputOrder;
+    if ($sortby eq 'container') {
+        @OutputOrder = @Statsarray;
     } else {
-        @list = sort (@list);
+        # $sortby is already defined, so we can charge ahead
+        if ($sortby =~ /^(title|part)$/i) {
+            # Alpha comparison
+            @OutputOrder = sort {
+                lc($a->{$sortby}) cmp lc($b->{$sortby}) ||
+                    lc($a->{'title'}) cmp lc($b->{'title'}) ||
+                        lc($a->{'part'}) cmp lc($b->{'part'});
+            } @Statsarray;
+        } else {
+            # Numerical comparison
+            @OutputOrder = sort {
+                my $retvalue = 0;
+                if ($b->{$sortby} eq 'nan') {
+                    if ($a->{$sortby} ne 'nan') {
+                        $retvalue = -1;
+                    } else {
+                        $retvalue = 0;
+                    }
+                }
+                if ($a->{$sortby} eq 'nan') {
+                    if ($b->{$sortby} ne 'nan') {
+                        $retvalue = 1;
+                    }
+                }
+                if ($retvalue eq '0') {
+                    $retvalue = $b->{$sortby} <=> $a->{$sortby} ||
+                                lc($a->{'title'}) <=> lc($b->{'title'}) ||
+                                lc($a->{'part'})  <=> lc($b->{'part'});
+                }
+                $retvalue;
+            } @Statsarray;
+        }
     }
-    my $cIdx=0;
+    $option .= 'no part' if (! $show_part);
+    my $num_output = 0;
+    #
+    # output the headers
+    $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n");
+    $r->print('<table border="0" cellpadding="3">'."\n");
+    my $Str = &statistics_table_header($option.' sortable');
+    $r->print('<tr bgcolor="#FFFFE6">'.$Str."</tr>\n");
+    #
+    foreach my $rowdata (@OutputOrder) {
+        $num_output++;
+        if ($num_output % 25 == 0) {
+            $r->print("</table>\n</td></tr></table>\n");
+            #
+            $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n");
+            $r->print('<table border="0" cellpadding="3">'."\n");
+            my $Str = &statistics_table_header($option.' sortable');
+            $r->print('<tr bgcolor="#FFFFE6">'.$Str."</tr>\n");
+            $r->rflush();
+        }
+        $r->print('<tr>'.&statistics_html_table_data($rowdata,$option).
+                  "</tr>\n");
+    }
+    $r->print("</table>\n");
+    $r->print("</td></tr></table>\n");
+    $r->rflush();
+    #
+    return;
+}
+
+###############################################
+###############################################
+
+=pod 
+
+=item &output_excel()
+
+Presents the statistical data in an Excel 95 compatable spreadsheet file.
 
-    if ( $pos == 0 ) {
-	foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
-	    if($cache->{'ProblemStatisticsMaps'} ne 'All Maps'  &&
-	       $cache->{'ProblemStatisticsMaps'} ne $cache->{$sequence.':title'}) {
-		next;
-	    }
-	    if ($cIdx==$p_count) {
-		return \%TempCache;
-	    }
-	    $r->print(&CreateProblemStatisticsTableHeading(
-                                             $cache->{'DisplayFormat'}, 
-                                             $cache->{$sequence.':source'},
-                                             $cache->{$sequence.':title'}, 
-                                             $headings,$r));
-
-	    my ($tar)=split(/\&/,$list[$cIdx]);
-	    $tar=~s/\+//eg;
-	    my ($SqOrd)=split(/\@/,$tar);
-	    $sequence+=100;
-	    while ($SqOrd==$sequence && $cIdx<$p_count) {
-		my($Pre, $Post) = split(/\+/,$list[$cIdx]); 
-		&TableRow($cache,$Post,$cIdx,$cIdx,$r,$color,\%TempCache);
-		$cIdx++;
-		my ($tar)=split(/\&/,$list[$cIdx]);
-		$tar=~s/\+//eg;
-		($SqOrd)=split(/\@/,$tar);
-	    }
-	    &CloseTable($cache,$r);
-	}
-    }
-    else {
-        $r->print(&CreateProblemStatisticsTableHeading(
-                                             $cache->{'DisplayFormat'}, 
-                                             'Sorted by: ',
-					     $headings->{$pos-1},
-                                             $headings,$r));
-	for ( my $nIndex = 0; $nIndex < $p_count; $nIndex++ ) {
-	    my($Pre, $Post) = split(/\+/,$list[$nIndex]);
-	    &TableRow($cache,$Post,$nIndex,$nIndex,$r,$color,\%TempCache);
-	} 
-	&CloseTable($cache,$r);
-    }
-
-    return \%TempCache;
-}
-=cut
-
-sub TableRow {
-    my ($displayFormat,$Str,$RealIdx,$r,$color)=@_;
-    my($ref,$title,$source,$StdNo,$TotalTries,$MxTries,$Avg,$YES,$Override,
-       $Wrng,$DoD,$SD,$Sk,$_D1,$_D2,$DiscNo,$Prob)=split(/\&/,$Str);	
-    my $Ptr;
-    if($displayFormat eq 'Display CSV Format') {
-        $Ptr="\n".'<br>'.
-             "\n".'"'.$RealIdx.'",'.
-             "\n".'"'.$title.'",'.
-             "\n".'"'.$source.'",'.
-             "\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.'"';
+=cut
 
-        $r->print("\n".$Ptr);
+###############################################
+###############################################
+sub output_excel {
+    my ($r) = @_;
+    my $filename = '/prtspool/'.
+        $ENV{'user.name'}.'_'.$ENV{'user.domain'}.'_'.
+            time.'_'.rand(1000000000).'.xls';
+    #
+    my $excel_workbook = undef;
+    my $excel_sheet = undef;
+    #
+    my $rows_output = 0;
+    my $cols_output = 0;
+    #
+    # Create sheet
+    $excel_workbook = Spreadsheet::WriteExcel->new('/home/httpd'.$filename);
+    #
+    # Check for errors
+    if (! defined($excel_workbook)) {
+        $r->log_error("Error creating excel spreadsheet $filename: $!");
+        $r->print("Problems creating new Excel file.  ".
+                  "This error has been logged.  ".
+                  "Please alert your LON-CAPA administrator");
+        return ;
+    }
+    #
+    # 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);
+    }
+    $excel_sheet = $excel_workbook->addworksheet($sheetname);
+    #
+    # 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 {
-        $Ptr="\n".'<tr>'.
-             "\n".'<td bgcolor="#ffffe6">'.$RealIdx.'</td>'.
-             "\n".'<td bgcolor="#ffffe6">'.$ref.'</td>'.
-             "\n".'<td bgcolor='.$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>' );
+        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);
+    #
+    # Put the date in there too
+    $excel_sheet->write($rows_output,$cols_output++,
+                        'Compiled on '.localtime(time));
+    #
+    $rows_output++; 
+    $cols_output=0;
+    #
+    # Add the headers
+    foreach my $field (@Fields) {
+        next if ($field->{'name'} eq 'problem_num');
+        $excel_sheet->write($rows_output,$cols_output++,$field->{'title'});
+    }
+    $rows_output++;
+    #
+    # Write the data
+    my $problem_num=0;
+    foreach my $sequence (&Apache::lonstatistics::Sequences_with_Assess()) {
+        next if ($sequence->{'num_assess'}<1);
+        foreach my $resource (@{$sequence->{'contents'}}) {
+            next if ($resource->{'type'} ne 'assessment');
+            foreach my $part (@{$resource->{'parts'}}) {
+                $cols_output=0;
+                $problem_num++;
+                my $data = &get_statistics($sequence,$resource,$part,
+                                           $problem_num);
+                #
+                if (!defined($part) || $part eq '') {
+                    $part = ' ';
+                }
+                foreach my $field (@Fields) {
+                    next if ($field->{'name'} eq 'problem_num');
+                    $excel_sheet->write($rows_output,$cols_output++,
+                                        $data->{$field->{'name'}});
+                }
+                $rows_output++;
+            }
+        }
+    }
+    #
+    # Write the excel file
+    $excel_workbook->close();
+    # Tell the user where to get their excel file
+    $r->print('<br />'.
+              '<a href="'.$filename.'">Your Excel spreadsheet.</a>'."\n");
+    $r->rflush();
     return;
 }
 
-# For loading the colored table for display or un-colored for print
-sub setbgcolor {
-    my $PrintTable=shift;
-    my %color;
-    if ($PrintTable){
-	$color{"gb"}="#FFFFFF";
-	$color{"red"}="#FFFFFF";
-	$color{"yellow"}="#FFFFFF";
-	$color{"green"}="#FFFFFF";
-	$color{"purple"}="#FFFFFF";
-    } else {
-	$color{"gb"}="#DDFFFF";
-	$color{"red"}="#FFDDDD";
-	$color{"yellow"}="#EEFFCC";
-	$color{"green"}="#DDFFDD";
-	$color{"purple"}="#FFDDFF";
-    }
-
-    return \%color;
-}
-
-sub ProblemStatisticsButtons {
-    my ($displayFormat)=@_;
-
-    my $Ptr = '<tr><td></td><td align="left">';
-    $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 Table Format" />'."\n";
-    } else {
-        $Ptr .= 'value="Display CSV Format" />'."\n";
+###############################################
+###############################################
+
+=pod 
+
+=item &statistics_html_table_data()
+
+Help function used to format the rows for HTML table output.
+
+=cut
+
+###############################################
+###############################################
+sub statistics_html_table_data {
+    my ($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>';
     }
-    $Ptr .= '</td></tr>';
+    return $row;
+}
 
-    return $Ptr;
+sub statistics_table_header {
+    my ($options) = @_;
+    my $header_row;
+    foreach my $field (@Fields) {
+        next if ($options =~ /no $field->{'name'}/);
+        $header_row .= '<th>';
+        if ($options =~ /sortable/ && 
+            exists($field->{'sortable'}) && $field->{'sortable'} eq 'yes') {
+            $header_row .= '<a href="javascript:'.
+                'document.Statistics.sortby.value='."'".$field->{'name'}."'".
+                    ';document.Statistics.submit();">';
+        }
+        $header_row .= $field->{'title'};
+        if ($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 .= 'plot</a>)';
+        }
+        $header_row .= '</th>';
+    }
+    return $header_row;
 }
 
+###############################################
+###############################################
+
+=pod 
+
+=item &plot_statistics()
+
+=cut
+
+###############################################
+###############################################
+sub plot_statistics {
+    my ($r,$datafield) = @_;
+    my @Data;
+    #
+    #
+    my $sortfield = undef;
+    my $title = undef;
+    foreach my $field (@Fields) {
+        if ($datafield eq $field->{'name'} &&
+            exists($field->{'graphable'}) && $field->{'graphable'} eq 'yes') {
+            $sortfield = $field->{'name'};
+            $title = $field->{'long_title'};
+        }
+    }
+    return if (! defined($sortfield) || $sortfield eq '');
+    #
+    my $Max = 0;
+    my $problem_num = 0;
+    foreach my $sequence (&Apache::lonstatistics::Sequences_with_Assess()) {
+        next if ($sequence->{'num_assess'}<1);
+        foreach my $resource (@{$sequence->{'contents'}}) {
+            next if ($resource->{'type'} ne 'assessment');
+            foreach my $part (@{$resource->{'parts'}}) {
+                my $problem_number++;
+                my $data = &get_statistics($sequence,$resource,$part,
+                                           $problem_num);
+                my $value = $data->{$sortfield};
+                $Max = $value if ($Max < $value);
+                push (@Data,$value);
+            }
+        }
+    }
+    #
+    # Print out plot request
+    my $yaxis = '';
+    if ($sortfield eq 'per_wrong') {
+        $yaxis = 'Percent';
+    }
+    #
+    # Determine appropriate value for $Max
+    if ($sortfield eq 'deg_of_diff') {
+        if ($Max > 0.5) {
+            $Max = 1;
+        } elsif ($Max > 0.2) {
+            $Max = 0.5;
+        } elsif ($Max > 0.1) {
+            $Max = 0.2;
+        }
+    } elsif ($sortfield eq 'per_wrong') {
+        if ($Max > 50) {
+            $Max = 100;
+        } elsif ($Max > 25) {
+            $Max = 50;
+        } elsif ($Max > 20) {
+            $Max = 25;
+        } elsif ($Max > 10) {
+            $Max = 20;
+        } elsif ($Max > 5) {
+            $Max = 10;
+        } else {
+            $Max = 5;
+        }
+    }
+    
+    $r->print("<p>".&DrawGraph(\@Data,$title,'Problem Number',$yaxis,
+                               $Max)."</p>\n");
+    #
+    # Print out the data
+    $ENV{'form.sortby'} = 'Contents';
+#    &output_html_ungrouped($r);
+    return;
+}
+
+###############################################
+###############################################
+
+=pod 
+
+=item &DrawGraph()
+
+=cut
+
+###############################################
+###############################################
+sub DrawGraph {
+    my ($values,$title,$xaxis,$yaxis,$Max)=@_;
+    $title = '' if (! defined($title));
+    $xaxis = '' if (! defined($xaxis));
+    $yaxis = '' if (! defined($yaxis));
+    #
+    my $sendValues = join(',', @$values);
+    my $sendCount = scalar(@$values);
+    $Max =1 if ($Max < 1);
+    if ( int($Max) < $Max ) {
+        $Max++;
+        $Max = int($Max);
+    }
+    my @GData = ($title,$xaxis,$yaxis,$Max,$sendCount,$sendValues);
+    return '<IMG src="/cgi-bin/graph.png?'.
+        (join('&', @GData)).'" border="1" />';
+}
+
+sub get_statistics {
+    my ($sequence,$resource,$part,$problem_num) = @_;
+    #
+    my $symb = $resource->{'symb'};
+    my $courseid = $ENV{'request.course.id'};
+    #
+    my $students = \@Apache::lonstatistics::Students;
+    if ($Apache::lonstatistics::SelectedSections[0] eq 'all') {
+        $students = undef;
+    }
+    my $data = &Apache::loncoursedata::get_problem_statistics
+                        ($students,$symb,$part,$courseid);
+    $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'});
+    #
+    return $data;
+}
+
+###############################################
+###############################################
+
+=pod 
+
+=item &ProblemStatisticsLegend()
+
+=cut
+
+###############################################
+###############################################
 sub ProblemStatisticsLegend {
     my $Ptr = '';
     $Ptr = '<table border="0">';
@@ -386,7 +911,7 @@ sub ProblemStatisticsLegend {
     $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 .= '<b>Max Tries</b></td>';
     $Ptr .= '<td>Largest number of tries for solving the problem by a student.';
     $Ptr .= '</td></tr><tr><td>';
     $Ptr .= '<b>Mean</b></td>';
@@ -418,8 +943,8 @@ sub ProblemStatisticsLegend {
     $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>[Criterion to group students into %27 Upper Students - ';
+    $Ptr .= 'and %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: ';
@@ -428,308 +953,10 @@ sub ProblemStatisticsLegend {
     $Ptr .= '<tr><td><b>Disc.</b></td>';
     $Ptr .= '<td>Number of Students had at least one discussion.';
     $Ptr .= '</td></tr></table>';
-
     return $Ptr;
 }
 
-#------- Processing upperlist and lowerlist according to each problem
-
-sub ExtractStudentData {
-    my ($cache, $students)=@_;
-
-#$Apache::lonxml::debug=1;
-#&Apache::lonhomework::showhash(%$cache);
-#$Apache::lonxml::debug=0;
-
-    my @problemList=();
-    my %problemData;
-    foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
-        if($cache->{'ProblemStatisticsMaps'} ne 'All Maps'  &&
-           $cache->{'ProblemStatisticsMaps'} ne $cache->{$sequence.':title'}) {
-            next;
-        }
-
-        foreach my $problemID (split(':', $cache->{$sequence.':problems'})) {
-            foreach my $part (split(/\:/,$cache->{$sequence.':'.
-                                                  $problemID.
-                                                  ':parts'})) {
-                my $id = $sequence.':'.$problemID.':'.$part;
-                push(@problemList, $id);
-                my $totalTries = 0;
-                my $totalAwarded = 0;
-                my $correct = 0;
-                my $correctByOverride = 0;
-                my $studentCount = 0;
-                my $maxTries = 0;
-                my $totalFirst = 0;
-                my @studentTries=();
-                foreach(@$students) {
-                    my $code = $cache->{"$_:$problemID:$part:code"};
-
-                    if(defined($cache->{$_.':error'}) || $code eq ' ' ||
-                       $cache->{"$_:$problemID:NoVersion"} eq 'true') {
-                        next;
-                    }
-
-                    $studentCount++;
-                    my $tries =  $cache->{"$_:$problemID:$part:tries"};
-                    if($maxTries < $tries) {
-                        $maxTries = $tries;
-                    }
-                    $totalTries += $tries;
-                    push(@studentTries, $tries);
-
-                    my $awarded = $cache->{"$_:$problemID:$part:awarded"};
-                    $totalAwarded += $awarded;
-
-                    if($code eq '*') {
-                        $correct++;
-                        if($tries == 1) {
-                            $totalFirst++;
-                        }
-                    } elsif($code eq '+') {
-                        $correctByOverride++;
-                    }
-                }
-
-                $problemData{$id.':sequenceTitle'} = 
-                    $cache->{$sequence.':title'};
-                $problemData{$id.':studentCount'} = $studentCount;
-                $problemData{$id.':totalTries'} = $totalTries;
-                $problemData{$id.':studentTries'} = \@studentTries;
-                $problemData{$id.':totalAwarded'} = $totalAwarded;
-                $problemData{$id.':correct'} = $correct;
-                $problemData{$id.':correctByOverride'} = $correctByOverride;
-                $problemData{$id.':wrong'} = $studentCount - 
-                                             ($correct + $correctByOverride);
-                $problemData{$id.':maxTries'} = $maxTries;
-                $problemData{$id.':totalFirst'} = $totalFirst;
-            }
-        }
-    }
-
-    $problemData{'problemList'} = \@problemList;
-#                $Discussed=0;
-#                if($Discuss->{"$name:$problem"}) {
-#		    $TotDiscuss++;
-#                    $Discussed=1;
-#                }
-
-    return \%problemData;
-}
-
-sub SortProblems {
-    my ($problemData,$sortBy,$ascend)=@_;
-
-    if($sortBy eq "Homework Sets Order") {
-        return;
-    }
-
-    my $data;
-
-    if   ($sortBy eq "#Stdnts") { $data = ':studentCount'; }
-    elsif($sortBy eq "Tries")   { $data = ':totalTries'; }
-    elsif($sortBy eq "Mod")     { $data = ':maxTries'; }
-    elsif($sortBy eq "Mean")    { $data = ':mean'; }
-    elsif($sortBy eq "#YES")    { $data = ':correct'; }
-    elsif($sortBy eq "#yes")    { $data = ':correctByOverride'; }
-    elsif($sortBy eq "%Wrng")   { $data = ':percentWrong'; }
-    elsif($sortBy eq "DoDiff")  { $data = ':degreeOfDifficulty'; }
-    elsif($sortBy eq "S.D.")    { $data = ':standardDeviation'; }
-    elsif($sortBy eq "Skew.")   { $data = ':skewness'; }
-    elsif($sortBy eq "D.F.1st") { $data = ':discriminantFactor1'; }
-    elsif($sortBy eq "D.F.2nd") { $data = ':discriminantFactor2'; }
-    elsif($sortBy eq "Disc.")   { $data = ''; }
-    else                        { return; }
-
-    my $problems = $problemData->{'problemList'};
-    my @orderedProblems = 
-        sort { $problemData->{$a.$data} <=> $problemData->{$b.$data} }
-             @$problems;
-    if($ascend eq 'Descending') {
-        @orderedProblems = reverse(@orderedProblems);
-    }
-
-    $problemData->{'problemList'} = \@orderedProblems;
-
-    return;
-}
-
-sub CalculateStatistics {
-    my ($data)=@_;
-
-    my $problems = $data->{'problemList'};
-    foreach(@$problems) {
-        # Mean
-        $data->{$_.':mean'} = ($data->{$_.':studentCount'}) ? 
-            ($data->{$_.':totalTries'} / $data->{$_.':studentCount'}) : 0;
-
-        # %Wrong
-        $data->{$_.':percentWrong'} = ($data->{$_.':studentCount'}) ?
-            (($data->{$_.':wrong'} / $data->{$_.':studentCount'}) * 100.0) : 
-            100.0;
-
-        # Degree of Difficulty
-        $data->{$_.':degreeOfDifficulty'} = ($data->{$_.':totalTries'}) ?
-            (1 - (($data->{$_.':correct'} + $data->{$_.':correctByOverride'}) /
-                  $data->{$_.':totalTries'})) : 0;
-
-        # Factor in mean
-        my $studentTries = $data->{$_.':studentTries'};
-        foreach(my $index=0; $index < scalar(@$studentTries); $index++) {
-            $studentTries->[$index] -= $data->{$_.':mean'};
-        }
-        my $sumSquared = 0;
-        my $sumCubed = 0;
-        foreach(@$studentTries) {
-            my $squared = ($_ * $_);
-            my $cubed = ($squared * $_);
-            $sumSquared += $squared;
-            $sumCubed += $cubed;
-        }
-
-        # Standard deviation
-        $data->{$_.':standardDeviation'} = ($data->{$_.':studentCount'} - 1) ?
-            ((sqrt($sumSquared)) / ($data->{$_.':studentCount'} - 1)) : 0;
-
-        # Skewness
-        my $standardDeviation = $data->{$_.':standardDeviation'};
-        $data->{$_.':skewness'} = ($data->{$_.':standardDeviation'}) ?
-            (((sqrt($sumSquared)) / $data->{$_.':studentCount'}) / 
-             ($standardDeviation * $standardDeviation * $standardDeviation)) :
-             0;
-
-        # Discrimination Factor 1
-        $data->{$_.':discriminationFactor1'} = 0;
-
-        # Discrimination Factor 2
-        $data->{$_.':discriminationFactor2'} = 0;
-    }
-
-    return;
-}
-
-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) {
-#        $jr->print("<br> $nIndex) $sortedList[$nIndex]");
-	($Problem,$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).':'.($Sum2/$nStudent);
-#        $jr->print("<br> $nIndex) $Temp --> ($nStudent) $Proc{$Temp}");
-	$Sum1=0;
-	$Sum2=0;
-	$nStudent=0;
-    }
-
-    return %Proc;
-}
-
-#------- Creating Discimination factor   
-sub Discriminant {
-    my ($discriminant)=@_;
-    my @discriminantKeys=keys(%$discriminant);
-    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 $str=$discriminant->{$key};
-            foreach(split(/\&/,$str)){
-                if($_) {
-                    if($low<$UpCnt) { push(@LowList,$_); }
-                    else            { push(@UpList,$_);  }
-                }
-            }
-        }
-    }
-    my %DisUp =  &ProcessDiscriminant(\@UpList);
-    my %DisLow = &ProcessDiscriminant(\@LowList);
-
-    return (\%DisUp, \%DisLow);
-}   
-
 #---- END Problem Statistics Web Page ----------------------------------------
 
-#---- Problem Statistics Graph Web Page --------------------------------------
-
-# ------------------------------------------- Prepare data for Graphical chart
-
-sub BuildGraphicChart {
-    my ($ylab,$r,$cacheDB)=@_;
-    my %cache;
-    my $Col;
-    my $data='';
-    my $count = 0;
-    my $Max = 0;
-
-    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
-        return '<html><body>Unable to tie database.</body></html>';
-    }
-   
-    my $p_count = $cache{'ProblemCount'};
-
-    for ( my $k=0; $k<$p_count;$k++) {
-        my @Temp=split(/\:/,$cache{'GraphGif:'.$k});
-        my $inf = $Temp[$Col]; 
-	if ( $Max < $inf ) {$Max = $inf;}
-      	$data .= $inf.',';
-       	$count++;
-    }
-    untie(%cache);
-#    $r->print("<br>count=$p_count >>data= $data");
-
-    if ( $Max > 1 ) { 
-	$Max += (10 - $Max % 10);
-      	$Max = int($Max);
-    } else { $Max = 1; }
-
-    my $cid=$ENV{'request.course.id'};
-
-    if ( $ylab eq 'DoDiff Graph' ) {
-	$ylab = 'Degree-of-Difficulty';
-	$Col = 0;
-    } else {
-	$ylab = 'Wrong-Percentage';
-	$Col = 1;
-    }
-    my $Course = $ENV{'course.'.$cid.'.description'};
-    $Course =~ s/\ /"_"/eg;
-    my $GData=$Course.'&'.'Problems#'.'&'.$ylab.'&'.
-	      $Max.'&'.$count.'&'.$data;
-
-    $r->print('<IMG src="/cgi-bin/graph.gif?'.$GData.'" />');
-
-    return;
-}
-
 1;
 __END__