1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 2009, 2011, 2014, 2015 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/>. */
18 #include "math/chart-geometry.h"
19 #include "output/charts/plot-hist.h"
22 #include <gsl/gsl_randist.h>
24 #include "data/val-type.h"
25 #include "output/cairo-chart.h"
27 #include "gl/xvasprintf.h"
28 #include "gl/minmax.h"
31 #define _(msgid) gettext (msgid)
33 /* Write the legend of the chart */
35 histogram_write_legend (cairo_t *cr, const struct xrchart_geometry *geom,
36 double n, double mean, double stddev)
38 double y = geom->axis[SCALE_ORDINATE].data_max - geom->font_size;
43 char *buf = xasprintf (_("Mean"));
44 cairo_move_to (cr,geom->legend_left, y);
45 xrchart_label (cr, 'l', 'b', geom->font_size, buf);
46 y -= geom->font_size * 1.5;
48 buf = xasprintf ("%g", mean);
49 cairo_move_to (cr,geom->legend_left, y);
50 xrchart_label (cr, 'l', 'b', geom->font_size, buf);
51 y -= geom->font_size * 2.0;
57 char *buf = xasprintf (_("Std Dev"));
58 cairo_move_to (cr, geom->legend_left, y);
59 xrchart_label (cr, 'l', 'b', geom->font_size, buf);
61 y -= geom->font_size * 1.5;
62 buf = xasprintf ("%g", stddev);
63 cairo_move_to (cr, geom->legend_left, y);
64 xrchart_label (cr, 'l', 'b', geom->font_size, buf);
66 y -= geom->font_size * 2.0;
71 char *buf = xasprintf (_("N = %.0f"), n);
72 cairo_move_to (cr, geom->legend_left, y);
73 xrchart_label (cr, 'l', 'b', geom->font_size, buf);
81 hist_draw_bar (cairo_t *cr, const struct xrchart_geometry *geom,
82 const gsl_histogram *h, int bar)
88 assert (0 == gsl_histogram_get_range (h, bar, &lower, &upper));
89 assert (upper >= lower);
92 (lower - geom->axis[SCALE_ABSCISSA].min) * geom->axis[SCALE_ABSCISSA].scale
93 + geom->axis[SCALE_ABSCISSA].data_min;
94 const double width = (upper - lower) * geom->axis[SCALE_ABSCISSA].scale;
96 height = geom->axis[SCALE_ORDINATE].scale * gsl_histogram_get (h, bar);
100 geom->axis[SCALE_ORDINATE].data_min,
103 cairo_set_source_rgb (cr,
104 geom->fill_colour.red / 255.0,
105 geom->fill_colour.green / 255.0,
106 geom->fill_colour.blue / 255.0);
107 cairo_fill_preserve (cr);
113 xrchart_draw_histogram (const struct chart *chart, cairo_t *cr,
114 struct xrchart_geometry *geom)
116 struct histogram_chart *h = to_histogram_chart (chart);
120 xrchart_write_title (cr, geom, _("HISTOGRAM"));
122 xrchart_write_ylabel (cr, geom, _("Frequency"));
123 xrchart_write_xlabel (cr, geom, chart_get_title (chart));
125 if (h->gsl_hist == NULL)
127 /* Probably all values are SYSMIS. */
131 if (! xrchart_write_yscale (cr, geom, 0, gsl_histogram_max_val (h->gsl_hist)))
133 if (! xrchart_write_xscale (cr, geom, gsl_histogram_min (h->gsl_hist),
134 gsl_histogram_max (h->gsl_hist)))
138 /* Draw the ticks and compute if the rendered tick text is wider than the bin */
139 bins = gsl_histogram_bins (h->gsl_hist);
141 for (i = 0; i < bins; i++)
143 hist_draw_bar (cr, geom, h->gsl_hist, i);
146 histogram_write_legend (cr, geom, h->n, h->mean, h->stddev);
149 && h->n != SYSMIS && h->mean != SYSMIS && h->stddev != SYSMIS)
151 /* Draw the normal curve */
153 double ordinate_scale;
157 gsl_histogram_get_range (h->gsl_hist, 0, &x_min, &x_max);
158 binwidth = x_max - x_min;
160 /* The integral over the histogram is binwidth * sum(bin_i), while the integral over the pdf is 1 */
161 /* Therefore the pdf has to be scaled accordingly such that the integrals are equal */
162 ordinate_scale = binwidth * gsl_histogram_sum(h->gsl_hist);
164 /* Clip normal curve to the rectangle formed by the axes. */
166 cairo_rectangle (cr, geom->axis[SCALE_ABSCISSA].data_min, geom->axis[SCALE_ORDINATE].data_min,
167 geom->axis[SCALE_ABSCISSA].data_max - geom->axis[SCALE_ABSCISSA].data_min,
168 geom->axis[SCALE_ORDINATE].data_max - geom->axis[SCALE_ORDINATE].data_min);
171 cairo_move_to (cr, geom->axis[SCALE_ABSCISSA].data_min, geom->axis[SCALE_ORDINATE].data_min);
172 for (x = geom->axis[SCALE_ABSCISSA].min;
173 x <= geom->axis[SCALE_ABSCISSA].max;
174 x += (geom->axis[SCALE_ABSCISSA].max - geom->axis[SCALE_ABSCISSA].min) / 100.0)
176 const double y = gsl_ran_gaussian_pdf (x - h->mean, h->stddev) * ordinate_scale;
177 /* Transform to drawing coordinates */
178 const double x_pos = (x - geom->axis[SCALE_ABSCISSA].min) * geom->axis[SCALE_ABSCISSA].scale + geom->axis[SCALE_ABSCISSA].data_min;
179 const double y_pos = (y - geom->axis[SCALE_ORDINATE].min) * geom->axis[SCALE_ORDINATE].scale + geom->axis[SCALE_ORDINATE].data_min;
180 cairo_line_to (cr, x_pos, y_pos);