--- loncom/interface/statistics/lonproblemstatistics.pm	2002/08/13 00:37:18	1.19
+++ loncom/interface/statistics/lonproblemstatistics.pm	2002/08/15 14:15:20	1.30
@@ -1,7 +1,7 @@
 # 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 1.30 2002/08/15 14:15:20 stredwic Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -45,18 +45,132 @@ use GDBM_File;
 
 my $jr;
 
-sub BuildProblemStatisticsPage {
+sub InitializeProblemStatistics {
     my ($cacheDB, $students, $courseID, $c, $r)=@_;
     my %cache;
 
     $jr = $r;
 
     unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
-        return '<html><body>Unable to tie database.</body></html>';
+        $r->print('Unable to tie database1.');
+        return ('ERROR', undef);
+    }
+
+    # Remove students who don't have the proper section.
+    my @sectionsSelected = split(':',$cache{'sectionsSelected'});
+    for(my $studentIndex=((scalar @$students)-1); $studentIndex>=0;
+        $studentIndex--) {
+        my $value = $cache{$students->[$studentIndex].':section'};
+        my $found = 0;
+        foreach (@sectionsSelected) {
+            if($_ eq 'none') {
+                if($value eq '' || !defined($value) || $value eq ' ') {
+                    $found = 1;
+                    last;
+                }
+            } else {
+                if($value eq $_) {
+                    $found = 1;
+                    last;
+                }
+            }
+        }
+        if($found == 0) {
+            splice(@$students, $studentIndex, 1);
+        }
+    }
+
+    my $isNotCached = 0;
+    my $lastStatus = (defined($cache{'StatisticsLastStatus'})) ?
+                     $cache{'StatisticsLastStatus'} : 'Nothing';
+    my $whichStudents = join(':::',sort(@$students));
+    if(!defined($cache{'StatisticsCached'}) || 
+       $lastStatus ne $cache{'Status'} ||
+       $whichStudents ne $cache{'StatisticsWhichStudents'}) {
+        $isNotCached = 1;
+    }
+
+    untie(%cache);
+    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT(),0640)) {
+        $r->print('Unable to tie database.2');
+        return ('ERROR', undef);
+    }
+    if($isNotCached && defined($cache{'StatisticsCached'})) {
+        my @statkeys = split(':::', $cache{'StatisticsKeys'});
+        delete $cache{'StatisticsKeys'};
+        delete $cache{'StatisticsCached'};
+        foreach(@statkeys) {
+            delete $cache{$_};
+        }
+    }
+
+    untie(%cache);
+    if($isNotCached) {
+        &Apache::loncoursedata::DownloadStudentCourseDataSeparate($students,
+                                                                  'true',
+                                                                  $cacheDB,
+                                                                  'true', 
+                                                                  'true',
+                                                                  $courseID,
+                                                                  $r, $c);
+    }
+    if($c->aborted()) { return ('ERROR', undef); }
+
+    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
+        $r->print('Unable to tie database.3');
+        return ('ERROR', undef);
     }
+    my $problemData;
+    if($isNotCached) {
+        ($problemData) = &ExtractStudentData(\%cache, $students);
+        &CalculateStatistics($problemData, \%cache, $courseID);
+    }
+    untie(%cache);
+
+    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT(),0640)) {
+        $r->print('Unable to tie database.4');
+        return ('ERROR', undef);
+    }
+    if($isNotCached) {
+        foreach(keys(%$problemData)) {
+            $cache{$_} = $problemData->{$_};
+        }
+        $cache{'StatisticsKeys'} = join(':::', keys(%$problemData));
+        $cache{'StatisticsCached'} = 'true';
+        $cache{'StatisticsLastStatus'} = $cache{'Status'};
+        $cache{'StatisticsWhichStudents'} = $whichStudents;
+    }
+    untie(%cache);
+
+    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
+        $r->print('Unable to tie database.5');
+        return ('ERROR', undef);
+    }
+
+    my $orderedProblems = &SortProblems(\%cache, 
+                                        $cache{'ProblemStatisticsSort'},
+                                        $cache{'SortProblems'},
+                                        $cache{'ProblemStatisticsAscend'});
+    untie(%cache);
+
+    return ('OK', $orderedProblems);
+}
+
+sub BuildProblemStatisticsPage {
+    my ($cacheDB, $students, $courseID, $c, $r)=@_;
 
+    my @Header = ("Homework Sets Order","#Stdnts","Tries","Mod",
+                  "Mean","#YES","#yes","%Wrng","DoDiff",
+                  "S.D.","Skew.","D.F.1st","D.F.2nd");
+    my $color=&setbgcolor(0);
+    my %cache;
+
+    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
+        $r->print('Unable to tie database.6');
+        return;
+    }
     my $Ptr = '';
-    $Ptr .= '<table border="0"><tbody>';
+    $Ptr .= '<table border="0" cellspacing="5"><tbody>';
     $Ptr .= '<tr><td align="right"><b>Select Map</b></td>'."\n";
     $Ptr .= '<td align="left">';
     $Ptr .= &Apache::lonhtmlcommon::MapOptions(\%cache, 'ProblemStatistics',
@@ -69,55 +183,95 @@ sub BuildProblemStatisticsPage {
                                             'ProblemStatistics',
                                             'Statistics');
     $Ptr .= '</td></tr>'."\n";
-    $Ptr .= &ProblemStatisticsButtons($cache{'DisplayFormat'});
+    $Ptr .= '<tr><td align="right"><b>Select Sections</b>';
+    $Ptr .= '</td>'."\n";
+    $Ptr .= '<td align="left">'."\n";
+    my @sections = split(':',$cache{'sectionList'});
+    my @sectionsSelected = split(':',$cache{'sectionsSelected'});
+    $Ptr .= &Apache::lonhtmlcommon::MultipleSectionSelect(\@sections,
+                                                          \@sectionsSelected,
+                                                          'Statistics');
+    $Ptr .= '</td></tr>'."\n";
+    $Ptr .= &ProblemStatisticsButtons($cache{'DisplayFormat'}, 
+                                      $cache{'DisplayLegend'},
+                                      $cache{'SortProblems'});
     $Ptr .= '</table>';
-    $Ptr .= &ProblemStatisticsLegend();
+    if($cache{'DisplayLegend'} eq 'Show Legend') {
+        $Ptr .= &ProblemStatisticsLegend();
+    }
     $r->print($Ptr);
     $r->rflush();
-
     untie(%cache);
 
-    &Apache::loncoursedata::DownloadStudentCourseDataSeparate($students,'true',
-                                                              $cacheDB,'true', 
-                                                              'true',$courseID,
-                                                              $r, $c);
-    if($c->aborted()) { return; }
+    my ($result, $orderedProblems) =
+        &InitializeProblemStatistics($cacheDB, $students, $courseID, $c, $r);
+    if($result ne 'OK') {
+        return;
+    }
 
     unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
-        return '<html><body>Unable to tie database.</body></html>';
+        $r->print('Unable to tie database.6');
+        return;
     }
+    &BuildStatisticsTable(\%cache, $cache{'DisplayFormat'}, 
+                          $cache{'SortProblems'}, $orderedProblems, 
+                          \@Header, $r, $color);
+    untie(%cache);
 
-    my @Header = ("Homework Sets Order","#Stdnts","Tries","Mod",
-                  "Mean","#YES","#yes","%Wrng","DoDiff",
-                  "S.D.","Skew.","D.F.1st","D.F.2nd","Disc.");
-    my $color=&setbgcolor(0);
+    return;
+}
+
+sub BuildGraphicChart {
+    my ($graph,$cacheDB,$courseDescription,$students,$courseID,$r,$c)=@_;
+    my %cache;
+    my $max = 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, $color);
+    my ($result, undef) = 
+        &InitializeProblemStatistics($cacheDB, $students, $courseID, $c, $r);
+    if($result ne 'OK') {
+        return;
+    }
+
+    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
+        return 'Unable to tie database.7';
+    }
+   
+    my @problems = split(':::', $cache{'problemList'});
+    my @values = ();
+    foreach (@problems) {
+        my $data = 0;
+        if($graph eq 'DoDiffGraph') {
+            $data = sprintf("%.2f", $cache{$_.':degreeOfDifficulty'}),
+        } else {
+            $data = sprintf("%.1f", $cache{$_.':percentWrong'}),
+        }
+        if($max < $data) {
+            $max = $data;
+        }
+        push(@values, $data);
+    }
     untie(%cache);
 
-#    foreach (keys %$TempCache) {
-#        last if ($c->aborted());
-#        if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT(),0640)) {
-#	    $cache{$_}=$TempCache->{$_};
-#            untie(%cache);
-#        }
-#    }
+    my $sendValues = join(',', @values);
+    my $sendCount = scalar(@values);
 
-#    if($c->aborted()) { return; }
-#    untie(%cache);
+    my $title = '';
+    if($graph eq 'DoDiffGraph') {
+	$title = 'Degree-of-Difficulty';
+    } else {
+	$title = 'Wrong-Percentage';
+    }
+    my @GData = ($courseDescription, 'Problems', $title, $max, $sendCount, 
+                 $sendValues);
+
+    $r->print('</form>'."\n");
+    $r->print('<IMG src="/cgi-bin/graph.gif?'.(join('&', @GData)).
+              '" border="1" />');
+    $r->print('<form>'."\n");
 
     return;
 }
 
-
 #---- Problem Statistics Web Page ---------------------------------------
 
 sub CreateProblemStatisticsTableHeading {
@@ -127,7 +281,8 @@ sub CreateProblemStatisticsTableHeading
     $Str .= '<tr>'."\n";
     $Str .= '<th bgcolor="#ffffe6">P#</th>'."\n";
     foreach(@$headings) {
-	$Str .= '<th bgcolor="#ffffe6">'.'<a href="/adm/statistics?reportSelected=';
+	$Str .= '<th bgcolor="#ffffe6">';
+        $Str .= '<a href="/adm/statistics?reportSelected=';
         $Str .= &Apache::lonnet::escape('Problem Statistics');
         $Str .= '&ProblemStatisticsSort=';
         $Str .= &Apache::lonnet::escape($_).'">'.$_.'</a>&nbsp</th>'."\n";
@@ -138,197 +293,117 @@ sub CreateProblemStatisticsTableHeading
 }
 
 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));
-    } else {
-        $r->print('<br>');
-    }
+    my ($cache,$displayFormat,$sortProblems,$orderedProblems,$headings,
+        $r,$color)=@_;
 
     my $count = 1;
-    foreach(@$problems) {
+    my $currentSequence = -1;
+    foreach(@$orderedProblems) {
         my ($sequence,$problem,$part)=split(':', $_);
-#        my $problemRef = '<a href="'.$cache->{$problem.':source'}.
-#                '" target="_blank">'.$cache->{$problem.':title'}.'</a>';
+        if($cache->{'StatisticsMaps'} ne 'All Maps'  &&
+           $cache->{'StatisticsMaps'} ne $cache->{$sequence.':title'}) {
+            next;
+        }
+
+        if($currentSequence == -1 || 
+           ($sortProblems eq 'Sort Within Sequence' && 
+            $currentSequence != $sequence)) {
+            if($displayFormat ne 'Display CSV Format') {
+                if($currentSequence ne -1) {
+                    $r->print('</table>');
+                    $r->print('</td></tr></table><br>');
+                }
+                if($sortProblems eq 'Sort Within Sequence') {
+                    $r->print('<b>'.$cache->{$sequence.':title'}.'</b>');
+                }
+                $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n");
+                $r->print('<table border="0" cellpadding="3">'."\n");
+                $r->print(&CreateProblemStatisticsTableHeading($headings, $r));
+            } else {
+                if($sortProblems eq 'Sort Within Sequence') {
+                    $r->print('"'.$cache->{$sequence.':title'}.'"');
+                }
+                $r->print('<br>');
+            }
+            $currentSequence = $sequence;
+        }
 
-        my $ref = $cache->{$problem.':title'};
+        my $ref = '<a href="'.$cache->{$problem.':source'}.
+                  '" target="_blank">'.$cache->{$problem.':title'}.'</a>';
         my $title = $cache->{$problem.':title'};
-        my $source = 'source';
+        if($part != 0) {
+            $title .= ' Part '.$part;
+        }
+        my $source = $cache->{$problem.':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
+                       $cache->{$_.':studentCount'},
+                       $cache->{$_.':totalTries'},
+                       $cache->{$_.':maxTries'},
+                       $cache->{$_.':mean'},
+                       $cache->{$_.':correct'},
+                       $cache->{$_.':correctByOverride'},
+                       $cache->{$_.':percentWrong'},
+                       $cache->{$_.':degreeOfDifficulty'},
+                       $cache->{$_.':standardDeviation'},
+                       $cache->{$_.':skewness'},
+                       $cache->{$_.':discriminationFactor1'},
+                       $cache->{$_.':discriminationFactor2'});
+
         &TableRow($displayFormat,$tableData,$count,$r,$color);
-#        $GraphDat->{'GraphGif:'.($count-1)}=$DoD.':'.$Wrng;
+
         $count++;
     }
-#    $TempCache{'ProblemCount'}=$count;
-    if($cache->{'DisplayFormat'} ne 'Display CSV Format') {
+    if($displayFormat ne 'Display CSV Format') {
         $r->print('</table>'."\n");
-    }
-    $r->print('</td></tr></table>');
-#6666666
-#    close( OUT );
-#666666
-    return \%TempCache;
-}
-
-=pod
-sub CacheStatisticsTable {
-    my ($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].'+'.$key;
-    }
-    
-    if ($pos>0) {
-        @list = sort OrderedSort (@list);
+        $r->print('</td></tr></table>');
     } else {
-        @list = sort (@list);
-    }
-    my $cIdx=0;
-
-    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);
+        $r->print('<br>');
     }
 
-    return \%TempCache;
+    return;
 }
-=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);	
+       $Wrng,$DoD,$SD,$Sk,$_D1,$_D2)=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.'"';
+        $Ptr='"'.$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".
+             "<br>\n";
 
         $r->print("\n".$Ptr);
     } 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>' );
+        $Ptr='<tr>'."\n".
+             '<td bgcolor="#ffffe6">'.$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";
+        $r->print($Ptr.'</tr>'."\n");
     }
 
     return;
@@ -356,15 +431,29 @@ sub setbgcolor {
 }
 
 sub ProblemStatisticsButtons {
-    my ($displayFormat)=@_;
+    my ($displayFormat, $displayLegend, $sortProblems)=@_;
 
     my $Ptr = '<tr><td></td><td align="left">';
     $Ptr .= '<input type="submit" name="DoDiffGraph" ';
-    $Ptr .= 'value="DoDiff Graph" />'."\n";
-    $Ptr .= '&nbsp;&nbsp;&nbsp;';
+    $Ptr .= 'value="Degree of Difficulty" />'."\n";
+    $Ptr .= '</td><td align="left">';
     $Ptr .= '<input type="submit" name="PercentWrongGraph" ';
-    $Ptr .= 'value="%Wrong Graph" />'."\n";
-    $Ptr .= '&nbsp;&nbsp;&nbsp;';
+    $Ptr .= 'value="Percent Wrong" />'."\n";
+    $Ptr .= '</td></tr><tr><td></td><td>'."\n";
+    $Ptr .= '<input type="submit" name="SortProblems" ';
+    if($sortProblems eq 'Sort All Problems') {
+        $Ptr .= 'value="Sort Within Sequence" />'."\n";
+    } else {
+        $Ptr .= 'value="Sort All Problems" />'."\n";
+    }
+    $Ptr .= '</td><td align="left">';
+    $Ptr .= '<input type="submit" name="DisplayLegend" ';
+    if($displayLegend eq 'Show Legend') {
+        $Ptr .= 'value="Hide Legend" />'."\n";
+    } else {
+        $Ptr .= 'value="Show Legend" />'."\n";
+    }
+    $Ptr .= '</td><td align="left">';
     $Ptr .= '<input type="submit" name="DisplayCSVFormat" ';
     if($displayFormat eq 'Display CSV Format') {
         $Ptr .= 'value="Display Table Format" />'."\n";
@@ -432,23 +521,12 @@ sub ProblemStatisticsLegend {
     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.
@@ -492,11 +570,12 @@ sub ExtractStudentData {
                     }
                 }
 
+                my $studentTriesJoined = join(':::', @studentTries);
                 $problemData{$id.':sequenceTitle'} = 
                     $cache->{$sequence.':title'};
                 $problemData{$id.':studentCount'} = $studentCount;
                 $problemData{$id.':totalTries'} = $totalTries;
-                $problemData{$id.':studentTries'} = \@studentTries;
+                $problemData{$id.':studentTries'} = $studentTriesJoined;
                 $problemData{$id.':totalAwarded'} = $totalAwarded;
                 $problemData{$id.':correct'} = $correct;
                 $problemData{$id.':correctByOverride'} = $correctByOverride;
@@ -508,21 +587,55 @@ sub ExtractStudentData {
         }
     }
 
-    $problemData{'problemList'} = \@problemList;
-#                $Discussed=0;
-#                if($Discuss->{"$name:$problem"}) {
-#		    $TotDiscuss++;
-#                    $Discussed=1;
-#                }
+    my @upperStudents1=();
+    my @lowerStudents1=();
+    my @upperStudents2=();
+    my @lowerStudents2=();
+    my $upperCount = int(0.27*scalar(@$students));
+    # Discriminant Factor criterion 1
+    my $sortedStudents = &SortDivideByTries($students,$cache,':totalAwarded');
+
+    for(my $i=0; $i<$upperCount; $i++) {
+        push(@lowerStudents1, $sortedStudents->[$i]);
+        push(@upperStudents1, $sortedStudents->[(scalar(@$students)-$i-1)]);
+    }
+
+    $problemData{'studentsUpperListCriterion1'}=join(':::', @upperStudents1);
+    $problemData{'studentsLowerListCriterion1'}=join(':::', @lowerStudents1);
+
+    # Discriminant Factor criterion 2
+    $sortedStudents = &SortDivideByTries($students, $cache, ':totalSolved');
+
+    for(my $i=0; $i<$upperCount; $i++) {
+        push(@lowerStudents2, $sortedStudents->[$i]);
+        push(@upperStudents2, $sortedStudents->[(scalar(@$students)-$i-1)]);
+    }
+    $problemData{'studentsUpperListCriterion2'}=join(':::', @upperStudents2);
+    $problemData{'studentsLowerListCriterion2'}=join(':::', @lowerStudents2);
+
+    $problemData{'problemList'} = join(':::', @problemList);
 
     return \%problemData;
 }
 
+sub SortDivideByTries {
+    my ($toSort, $data, $sortOn)=@_;
+    my @orderedData = sort { ($data->{$a.':totalTries'}) ? 
+                             ($data->{$a.$sortOn}/$data->{$a.':totalTries'}):0
+                             <=>
+                             ($data->{$b.':totalTries'}) ? 
+                             ($data->{$b.$sortOn}/$data->{$b.':totalTries'}):0
+                           } @$toSort;
+
+    return \@orderedData;
+}
+
 sub SortProblems {
-    my ($problemData,$sortBy,$ascend)=@_;
+    my ($problemData,$sortBy,$sortProblems,$ascend)=@_;
 
+    my @problems = split(':::', $problemData->{'problemList'});
     if($sortBy eq "Homework Sets Order") {
-        return;
+        return \@problems;
     }
 
     my $data;
@@ -537,51 +650,85 @@ sub SortProblems {
     elsif($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;
+    elsif($sortBy eq "D.F.1st") { $data = ':discriminationFactor1'; }
+    elsif($sortBy eq "D.F.2nd") { $data = ':discriminationFactor2'; }
+    else                        { return \@problems; }
+
+    my %temp;
+    my @sequenceList=();
+    foreach(@problems) {
+        my ($sequence) = split(':', $_);
+
+        my @array=();
+        my $tempArray;
+        if(defined($temp{$sequence})) {
+            $tempArray = $temp{$sequence};
+        } else {
+            push(@sequenceList, $sequence);
+            $tempArray = \@array;
+            $temp{$sequence} = $tempArray;
+        }
+
+        push(@$tempArray, $_);
+    }
+
+    my @orderedProblems;
+    if($sortProblems eq "Sort Within Sequence") {
+        foreach(keys(%temp)) {
+            my $tempArray = $temp{$_};
+            my @tempOrder =
+                sort { $problemData->{$a.$data} <=> $problemData->{$b.$data} }
+            @$tempArray;
+            $temp{$_} = \@tempOrder;
+        }
+        foreach(@sequenceList) {
+            my $tempArray = $temp{$_};
+            @orderedProblems = (@orderedProblems, @$tempArray);
+        }
+    } else {
+        @orderedProblems = 
+            sort { $problemData->{$a.$data} <=> $problemData->{$b.$data} }
+        @problems;
+    }
+
     if($ascend eq 'Descending') {
         @orderedProblems = reverse(@orderedProblems);
     }
 
-    $problemData->{'problemList'} = \@orderedProblems;
-
-    return;
+    return \@orderedProblems;
 }
 
 sub CalculateStatistics {
-    my ($data)=@_;
+    my ($data, $cache, $courseID)=@_;
 
-    my $problems = $data->{'problemList'};
-    foreach(@$problems) {
+    my @problems = split(':::', $data->{'problemList'});
+    foreach(@problems) {
         # Mean
-        $data->{$_.':mean'} = ($data->{$_.':studentCount'}) ? 
+        my $mean = ($data->{$_.':studentCount'}) ? 
             ($data->{$_.':totalTries'} / $data->{$_.':studentCount'}) : 0;
+        $data->{$_.':mean'} = sprintf("%.2f", $mean);
 
         # %Wrong
-        $data->{$_.':percentWrong'} = ($data->{$_.':studentCount'}) ?
+        my $pw = ($data->{$_.':studentCount'}) ?
             (($data->{$_.':wrong'} / $data->{$_.':studentCount'}) * 100.0) : 
             100.0;
+        $data->{$_.':percentWrong'} = sprintf("%.1f", $pw);
 
         # Degree of Difficulty
-        $data->{$_.':degreeOfDifficulty'} = ($data->{$_.':totalTries'}) ?
+        my $dod = ($data->{$_.':totalTries'}) ?
             (1 - (($data->{$_.':correct'} + $data->{$_.':correctByOverride'}) /
                   $data->{$_.':totalTries'})) : 0;
 
+        $data->{$_.':degreeOfDifficulty'} = sprintf("%.2f", $dod);
+
         # Factor in mean
-        my $studentTries = $data->{$_.':studentTries'};
-        foreach(my $index=0; $index < scalar(@$studentTries); $index++) {
-            $studentTries->[$index] -= $data->{$_.':mean'};
+        my @studentTries = split(':::', $data->{$_.':studentTries'});
+        foreach(my $index=0; $index < scalar(@studentTries); $index++) {
+            $studentTries[$index] -= $mean;
         }
         my $sumSquared = 0;
         my $sumCubed = 0;
-        foreach(@$studentTries) {
+        foreach(@studentTries) {
             my $squared = ($_ * $_);
             my $cubed = ($squared * $_);
             $sumSquared += $squared;
@@ -589,147 +736,89 @@ sub CalculateStatistics {
         }
 
         # Standard deviation
-        $data->{$_.':standardDeviation'} = ($data->{$_.':studentCount'} - 1) ?
-            ((sqrt($sumSquared)) / ($data->{$_.':studentCount'} - 1)) : 0;
+        my $standardDeviation;
+        if($data->{$_.':studentCount'} - 1 > 0) {
+            $standardDeviation = (sqrt($sumSquared)) / 
+                                 ($data->{$_.':studentCount'} - 1);
+        } else {
+            $standardDeviation =  0.0;
+        }
+        $data->{$_.':standardDeviation'} = sprintf("%.1f", $standardDeviation);
 
         # Skewness
-        my $standardDeviation = $data->{$_.':standardDeviation'};
-        $data->{$_.':skewness'} = ($data->{$_.':standardDeviation'}) ?
-            (((sqrt($sumSquared)) / $data->{$_.':studentCount'}) / 
-             ($standardDeviation * $standardDeviation * $standardDeviation)) :
-             0;
+        my $skew;
+        if($standardDeviation > 0.0999 && $data->{$_.':studentCount'} > 0) {
+            $skew = (((sqrt($sumSquared)) / $data->{$_.':studentCount'}) / 
+                     ($standardDeviation * 
+                      $standardDeviation * 
+                      $standardDeviation));
+        } else {
+            $skew = 0.0;
+        }
 
-        # Discrimination Factor 1
-        $data->{$_.':discriminationFactor1'} = 0;
+        $data->{$_.':skewness'} = sprintf("%.1f", $skew);
 
-        # Discrimination Factor 2
-        $data->{$_.':discriminationFactor2'} = 0;
-    }
+        # Discrimination Factor 1
+        my ($sequence, $problem, $part) = split(':', $_);
 
-    return;
-}
+        my @upper1 = split(':::', $data->{'studentsUpperListCriterion1'});
+        my @lower1 = split(':::', $data->{'studentsLowerListCriterion1'});
 
-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 $upper1Sum=0;
+        foreach my $name (@upper1) {
+            $upper1Sum += $cache->{"$name:$problem:$part:awarded"};
         }
-    }
-    my %DisUp =  &ProcessDiscriminant(\@UpList);
-    my %DisLow = &ProcessDiscriminant(\@LowList);
-
-    return (\%DisUp, \%DisLow);
-}   
+        $upper1Sum = (scalar(@upper1)) ? ($upper1Sum/(scalar(@upper1))) : 0;
 
-#---- END Problem Statistics Web Page ----------------------------------------
+        my $lower1Sum=0;
+        foreach my $name (@lower1) {
+            $lower1Sum += $cache->{"$name:$problem:$part:awarded"};
+        }
+        $lower1Sum = (scalar(@lower1)) ? ($lower1Sum/(scalar(@lower1))) : 0;
 
-#---- Problem Statistics Graph Web Page --------------------------------------
+        my $df1 = $upper1Sum - $lower1Sum;
+        $data->{$_.':discriminationFactor1'} = sprintf("%.2f", $df1);
 
-# ------------------------------------------- Prepare data for Graphical chart
+        # Discrimination Factor 2
+        my @upper2 = split(':::', $data->{'studentsUpperListCriterion2'});
+        my @lower2 = split(':::', $data->{'studentsLowerListCriterion2'});
 
-sub BuildGraphicChart {
-    my ($ylab,$r,$cacheDB)=@_;
-    my %cache;
-    my $Col;
-    my $data='';
-    my $count = 0;
-    my $Max = 0;
+        my $upper2Sum=0;
+        foreach my $name (@upper2) {
+            $upper2Sum += $cache->{"$name:$problem:$part:awarded"};
+        }
+        $upper2Sum = (scalar(@upper2)) ? ($upper2Sum/(scalar(@upper2))) : 0;
 
-    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
-        return '<html><body>Unable to tie database.</body></html>';
-    }
-   
-    my $p_count = $cache{'ProblemCount'};
+        my $lower2Sum=0;
+        foreach my $name (@lower2) {
+            $lower2Sum += $cache->{"$name:$problem:$part:awarded"};
+        }
+        $lower2Sum = (scalar(@lower2)) ? ($lower2Sum/(scalar(@lower2))) : 0;
 
-    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");
+        my $df2 = $upper2Sum - $lower2Sum;
+        $data->{$_.':discriminationFactor2'} = sprintf("%.2f", $df2);
 
-    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 %storestats;
+        my $Average = ($data->{$_.':studentCount'}) ? 
+            $data->{$_.':totalTries'}/$data->{$_.':studentCount'} : 0;
+        $storestats{$courseID.'___'.$cache->{$sequence.':source'}.
+                        '___timestamp'}=time;
+        $storestats{$courseID.'___'.$cache->{$sequence.':source'}.
+                        '___stdno'}=$data->{$_.':studentCount'};
+        $storestats{$courseID.'___'.$cache->{$sequence.':source'}.
+                        '___avetries'}=$Average;
+        $storestats{$courseID.'___'.$cache->{$sequence.':source'}.
+                        '___difficulty'}=$data->{$_.':degreeOfDifficulty'};
+        $cache->{$sequence.':source'} =~ /^(\w+)\/(\w+)/;
+        if($data->{$_.':studentCount'}) { 
+            &Apache::lonnet::put('resevaldata',\%storestats,$1,$2);
+        }
     }
-    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;
 }
 
+#---- END Problem Statistics Web Page ----------------------------------------
+
 1;
 __END__