From 936a316fd1dc5ff1f7b0d72d028de10e431382eb Mon Sep 17 00:00:00 2001
From: "Eugeniy E. Mikhailov" <evgmik@gmail.com>
Date: Thu, 10 May 2018 20:36:51 -0400
Subject: some heuristic for histogram with a small number of bins

---
 GradeBook_lib.tcl | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'GradeBook_lib.tcl')

diff --git a/GradeBook_lib.tcl b/GradeBook_lib.tcl
index 58d2b03..f459d9a 100755
--- a/GradeBook_lib.tcl
+++ b/GradeBook_lib.tcl
@@ -2330,6 +2330,8 @@ proc UpdateColumnGradesHistogram { columnname } {
 		set maxVal [::math::statistics::max $col_values ]; # fixme should it be _Max_Points_?
 		set minVal 0 
 		set barsNum 10;
+		set uniqNum [llength [lsort -unique $col_values]]
+		set barsNum [expr {min($uniqNum, $barsNum)}]; # heuristic about number of bars/intervals
 		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 ]
-- 
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