HISTOGRAMS: Fix bin width problems on large numbers of bins

[pspp] / src / language / stats / frequencies.q

diff --git a/src/language/stats/frequencies.q b/src/language/stats/frequencies.q
index 01247f518cdff07bea16ff1de5d24e14b1777a0b..b5ad8c47793eef15064a887023eead28732c8845 100644 (file)
--- a/src/language/stats/frequencies.q
+++ b/src/language/stats/frequencies.q
@@ -43,6 +43,8 @@
 #include "libpspp/str.h"
 #include "math/histogram.h"
 #include "math/moments.h"
+#include "math/chart-geometry.h"
+
 #include "output/chart-item.h"
 #include "output/charts/piechart.h"
 #include "output/charts/plot-hist.h"
@@ -497,14 +499,17 @@ postcalc (struct frq_proc *frq, const struct dataset *ds)
 
          histogram = freq_tab_to_hist (frq, &vf->tab, vf->var);
 
-          chart_item_submit (histogram_chart_create (
+         if ( histogram)
+           {
+             chart_item_submit (histogram_chart_create (
                                histogram->gsl_hist, var_to_string(vf->var),
                                vf->tab.valid_cases,
                                d[FRQ_MEAN],
                                d[FRQ_STDDEV],
                                frq->hist->draw_normal));
 
-         statistic_destroy (&histogram->parent);
+             statistic_destroy (&histogram->parent);
+           }
        }
 
       if (frq->pie)
@@ -699,7 +704,7 @@ frq_custom_grouped (struct lexer *lexer, struct dataset *ds, struct cmd_frequenc
            if (!lex_match (lexer, T_RPAREN))
              {
                free (v);
-               msg (SE, _("`)' expected after GROUPED interval list."));
+                lex_error_expecting (lexer, "`)'", NULL_SENTINEL);
                return 0;
              }
          }
@@ -1114,10 +1119,9 @@ freq_tab_to_hist (const struct frq_proc *frq, const struct freq_tab *ft,
 {
   double x_min, x_max, valid_freq;
   int i;
-
+  double bin_width;
   struct histogram *histogram;
   double iqr;
-  int bins;
 
   /* Find out the extremes of the x value, within the range to be included in
      the histogram, and sum the total frequency of those values. */
@@ -1137,19 +1141,13 @@ freq_tab_to_hist (const struct frq_proc *frq, const struct freq_tab *ft,
 
   /* Freedman-Diaconis' choice of bin width. */
   iqr = calculate_iqr (frq);
-  if (iqr != SYSMIS)
-    {
-      double bin_width = 2 * iqr / pow (valid_freq, 1.0 / 3.0);
-      bins = (x_max - x_min) / bin_width;
-      if (bins < 5)
-        bins = 5;
-      else if (bins > 400)
-        bins = 400;
-    }
-  else
-    bins = 5;
+  bin_width = 2 * iqr / pow (valid_freq, 1.0 / 3.0);
+
+  histogram = histogram_create (bin_width, x_min, x_max);
+
+  if ( histogram == NULL)
+    return NULL;
 
-  histogram = histogram_create (bins, x_min, x_max);
   for (i = 0; i < ft->n_valid; i++)
     {
       const struct freq *f = &ft->valid[i];