more conner cases covering in histogram generation

1 files changed, 15 insertions, 1 deletions

diff --git a/GradeBook_lib.tcl b/GradeBook_lib.tcl
index 7ca586f..129a0ea 100755
--- a/GradeBook_lib.tcl
+++ b/GradeBook_lib.tcl
@@ -2330,11 +2330,25 @@ proc UpdateColumnGradesHistogram { columnname } {
 	set col_values [GetGroupValuesInColumn student $columnname]
 	set col_values [LeaveOnlyNumbersInList $col_values]
 	if { 0 != [llength $col_values] } {
-		set maxVal [::math::statistics::max $col_values ]; # fixme should it be _Max_Points_?
 		set minVal 0 
+		set maxVal [getMaxPointsForColumn $columnname ]
+		if { $minVal >= $maxVal } {
+			# most likely column has maximum points undefined or zero
+			# like for bonuses or fudge columns
+			set maxVal [::math::statistics::max $col_values ]; # fixme should it be _Max_Points_?
+		}
+		if { $minVal >= $maxVal } {
+			set errorMessage "something really messed up with column $columnname min and max points, applying kludge recovery."
+			htmlErrorMsg $errorMessage
+			dbg  $errorMessage msg_level_critical [lindex [info level 0] 0]
+			# kludge/hack to make ::math::statistics::minmax-histogram-limits happy
+			set maxVal [expr {$minVal+1}]
+		}
 		set barsNum 10;
 		set uniqNum [llength [lsort -unique $col_values]]
 		set barsNum [expr {min($uniqNum, $barsNum)}]; # heuristic about number of bars/intervals
+		set barsNum [expr {max(2, $barsNum)}]; # at least 2 bars since we strip left and right
+
 		set limits [::math::statistics::minmax-histogram-limits $minVal $maxVal [incr barsNum]]
 		set limits [lrange $limits 1 end-1]; # shave first and last interval limits
 		set hist [::math::statistics::histogram $limits $col_values ]