1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 2009, 2011 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19 #include "output/charts/plot-hist.h"
21 #include <gsl/gsl_randist.h>
23 #include "data/val-type.h"
24 #include "output/cairo-chart.h"
26 #include "gl/xvasprintf.h"
29 #define _(msgid) gettext (msgid)
31 /* Write the legend of the chart */
33 histogram_write_legend (cairo_t *cr, const struct xrchart_geometry *geom,
34 double n, double mean, double stddev)
36 double y = geom->data_bottom;
41 char *buf = xasprintf ("N = %.2f", n);
42 cairo_move_to (cr, geom->legend_left, y);
43 xrchart_label (cr, 'l', 'b', geom->font_size, buf);
44 y += geom->font_size * 1.5;
50 char *buf = xasprintf ("Mean = %.1f", mean);
51 cairo_move_to (cr,geom->legend_left, y);
52 xrchart_label (cr, 'l', 'b', geom->font_size, buf);
53 y += geom->font_size * 1.5;
59 char *buf = xasprintf ("Std. Dev = %.2f", stddev);
60 cairo_move_to (cr, geom->legend_left, y);
61 xrchart_label (cr, 'l', 'b', geom->font_size, buf);
69 hist_draw_bar (cairo_t *cr, const struct xrchart_geometry *geom,
70 const gsl_histogram *h, int bar)
76 const size_t bins = gsl_histogram_bins (h);
77 const double x_pos = (geom->data_right - geom->data_left) * bar / (double) bins ;
78 const double width = (geom->data_right - geom->data_left) / (double) bins ;
80 assert ( 0 == gsl_histogram_get_range (h, bar, &lower, &upper));
82 assert ( upper >= lower);
84 height = gsl_histogram_get (h, bar) *
85 (geom->data_top - geom->data_bottom) / gsl_histogram_max_val (h);
87 cairo_rectangle (cr, geom->data_left + x_pos, geom->data_bottom,
90 cairo_set_source_rgb (cr,
91 geom->fill_colour.red / 255.0,
92 geom->fill_colour.green / 255.0,
93 geom->fill_colour.blue / 255.0);
94 cairo_fill_preserve (cr);
98 draw_tick (cr, geom, TICK_ABSCISSA,
99 x_pos + width / 2.0, "%g", (upper + lower) / 2.0);
103 xrchart_draw_histogram (const struct chart_item *chart_item, cairo_t *cr,
104 struct xrchart_geometry *geom)
106 struct histogram_chart *h = to_histogram_chart (chart_item);
110 xrchart_write_title (cr, geom, _("HISTOGRAM"));
112 xrchart_write_ylabel (cr, geom, _("Frequency"));
113 xrchart_write_xlabel (cr, geom, chart_item_get_title (chart_item));
115 if (h->gsl_hist == NULL)
117 /* Probably all values are SYSMIS. */
121 bins = gsl_histogram_bins (h->gsl_hist);
123 xrchart_write_yscale (cr, geom, 0, gsl_histogram_max_val (h->gsl_hist), 5);
125 for (i = 0; i < bins; i++)
126 hist_draw_bar (cr, geom, h->gsl_hist, i);
128 histogram_write_legend (cr, geom, h->n, h->mean, h->stddev);
131 && h->n != SYSMIS && h->mean != SYSMIS && h->stddev != SYSMIS)
133 /* Draw the normal curve */
135 double x_min, x_max, not_used;
136 double abscissa_scale;
137 double ordinate_scale;
140 gsl_histogram_get_range (h->gsl_hist, 0, &x_min, ¬_used);
141 range = not_used - x_min;
142 gsl_histogram_get_range (h->gsl_hist, bins - 1, ¬_used, &x_max);
144 abscissa_scale = (geom->data_right - geom->data_left) / (x_max - x_min);
145 ordinate_scale = (geom->data_top - geom->data_bottom) /
146 gsl_histogram_max_val (h->gsl_hist);
148 cairo_move_to (cr, geom->data_left, geom->data_bottom);
149 for (d = geom->data_left;
150 d <= geom->data_right;
151 d += (geom->data_right - geom->data_left) / 100.0)
153 const double x = (d - geom->data_left) / abscissa_scale + x_min;
154 const double y = h->n * range *
155 gsl_ran_gaussian_pdf (x - h->mean, h->stddev);
157 cairo_line_to (cr, d, geom->data_bottom + y * ordinate_scale);