1 /* PSPP - computes sample statistics.
2 Copyright (C) 2004 Free Software Foundation, Inc.
3 Written by John Darrington <john@darrington.wattle.id.au>
5 This program is free software; you can redistribute it and/or
6 modify it under the terms of the GNU General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 This program is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
20 /* If you add/modify any public symbols in this file, don't forget to
21 change the stubs in dummy-chart.c */
28 #include <gsl/gsl_histogram.h>
29 #include <gsl/gsl_randist.h>
36 #define _(msgid) gettext (msgid)
38 /* Write the legend of the chart */
40 histogram_write_legend(struct chart *ch, const struct normal_curve *norm)
46 pl_savestate_r(ch->lp);
48 sprintf(buf,"N = %.2f",norm->N);
49 pl_move_r(ch->lp, ch->legend_left, ch->data_bottom);
50 pl_alabel_r(ch->lp,0,'b',buf);
52 sprintf(buf,"Mean = %.1f",norm->mean);
53 pl_fmove_r(ch->lp,ch->legend_left,ch->data_bottom + ch->font_size * 1.5);
54 pl_alabel_r(ch->lp,0,'b',buf);
56 sprintf(buf,"Std. Dev = %.2f",norm->stddev);
57 pl_fmove_r(ch->lp,ch->legend_left,ch->data_bottom + ch->font_size * 1.5 * 2);
58 pl_alabel_r(ch->lp,0,'b',buf);
60 pl_restorestate_r(ch->lp);
63 static void hist_draw_bar(struct chart *ch, const gsl_histogram *hist, int bar);
67 hist_draw_bar(struct chart *ch, const gsl_histogram *hist, int bar)
78 const size_t bins = gsl_histogram_bins(hist);
79 const double x_pos = (ch->data_right - ch->data_left) * bar / (double) bins ;
80 const double width = (ch->data_right - ch->data_left) / (double) bins ;
83 assert ( 0 == gsl_histogram_get_range(hist, bar, &lower, &upper));
85 assert( upper >= lower);
87 height = gsl_histogram_get(hist, bar) *
88 (ch->data_top - ch->data_bottom) / gsl_histogram_max_val(hist);
90 pl_savestate_r(ch->lp);
91 pl_move_r(ch->lp,ch->data_left, ch->data_bottom);
92 pl_fillcolorname_r(ch->lp, ch->fill_colour);
93 pl_filltype_r(ch->lp,1);
98 x_pos + width, height);
100 pl_restorestate_r(ch->lp);
104 snprintf(buf,5,"%g",(upper + lower) / 2.0);
105 draw_tick(ch, TICK_ABSCISSA,
106 x_pos + width / 2.0, buf);
115 histogram_plot(const gsl_histogram *hist,
116 const char *factorname,
117 const struct normal_curve *norm, short show_normal)
124 bins = gsl_histogram_bins(hist);
127 chart_write_title(ch, _("HISTOGRAM"));
129 chart_write_ylabel(ch, _("Frequency"));
130 chart_write_xlabel(ch, factorname);
132 chart_write_yscale(ch, 0, gsl_histogram_max_val(hist), 5);
134 for ( i = 0 ; i < bins ; ++i )
135 hist_draw_bar(ch, hist, i);
137 histogram_write_legend(ch, norm);
141 /* Draw the normal curve */
144 double x_min, x_max, not_used ;
145 double abscissa_scale ;
146 double ordinate_scale ;
149 gsl_histogram_get_range(hist, 0, &x_min, ¬_used);
150 range = not_used - x_min;
151 gsl_histogram_get_range(hist, bins - 1, ¬_used, &x_max);
152 assert(range == x_max - not_used);
154 abscissa_scale = (ch->data_right - ch->data_left) / (x_max - x_min);
155 ordinate_scale = (ch->data_top - ch->data_bottom) /
156 gsl_histogram_max_val(hist) ;
158 pl_move_r(ch->lp, ch->data_left, ch->data_bottom);
159 for( d = ch->data_left;
160 d <= ch->data_right ;
161 d += (ch->data_right - ch->data_left) / 100.0)
163 const double x = (d - ch->data_left) / abscissa_scale + x_min ;
164 const double y = norm->N * range *
165 gsl_ran_gaussian_pdf(x - norm->mean, norm->stddev);
167 pl_fcont_r(ch->lp, d, ch->data_bottom + y * ordinate_scale);
170 pl_endpath_r(ch->lp);