/* PSPP - a program for statistical analysis.
- Copyright (C) 2009, 2011, 2014 Free Software Foundation, Inc.
+ Copyright (C) 2009, 2011, 2014, 2015 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
static void
hist_draw_bar (cairo_t *cr, const struct xrchart_geometry *geom,
- const gsl_histogram *h, int bar, const char *tick_format_string,
- const double tickscale, const bool tickoversize)
+ const gsl_histogram *h, int bar)
{
double upper;
double lower;
double height;
- const size_t bins = gsl_histogram_bins (h);
-
- const double x_pos =
- (geom->axis[SCALE_ABSCISSA].data_max - geom->axis[SCALE_ABSCISSA].data_min) *
- bar / (double) bins ;
-
- const double width =
- (geom->axis[SCALE_ABSCISSA].data_max - geom->axis[SCALE_ABSCISSA].data_min) / (double) bins ;
-
assert ( 0 == gsl_histogram_get_range (h, bar, &lower, &upper));
-
assert ( upper >= lower);
+ const double x_pos =
+ (lower - geom->axis[SCALE_ABSCISSA].min) * geom->axis[SCALE_ABSCISSA].scale
+ + geom->axis[SCALE_ABSCISSA].data_min;
+ const double width = (upper - lower) * geom->axis[SCALE_ABSCISSA].scale;
+
height = geom->axis[SCALE_ORDINATE].scale * gsl_histogram_get (h, bar);
cairo_rectangle (cr,
- geom->axis[SCALE_ABSCISSA].data_min + x_pos,
+ x_pos,
geom->axis[SCALE_ORDINATE].data_min,
width, height);
cairo_save (cr);
cairo_fill_preserve (cr);
cairo_restore (cr);
cairo_stroke (cr);
-
- draw_tick (cr, geom, SCALE_ABSCISSA, tickoversize,
- x_pos + width / 2.0, tick_format_string, (upper+lower)/2.0*tickscale);
-
}
void
struct histogram_chart *h = to_histogram_chart (chart_item);
int i;
int bins;
- char *tick_format_string;
- char *test_text;
- double width, left_width, right_width, unused;
- double tickscale;
- bool tickoversize;
xrchart_write_title (cr, geom, _("HISTOGRAM"));
}
xrchart_write_yscale (cr, geom, 0, gsl_histogram_max_val (h->gsl_hist));
+ xrchart_write_xscale (cr, geom, gsl_histogram_min (h->gsl_hist),
+ gsl_histogram_max (h->gsl_hist));
+
/* Draw the ticks and compute if the rendered tick text is wider than the bin */
bins = gsl_histogram_bins (h->gsl_hist);
- tick_format_string = chart_get_ticks_format (gsl_histogram_max (h->gsl_hist),
- gsl_histogram_min (h->gsl_hist),
- bins,
- &tickscale);
- test_text = xasprintf(tick_format_string, gsl_histogram_max (h->gsl_hist)*tickscale);
- xrchart_text_extents (cr, geom, test_text, &right_width, &unused);
- free(test_text);
- test_text = xasprintf(tick_format_string, gsl_histogram_min (h->gsl_hist)*tickscale);
- xrchart_text_extents (cr, geom, test_text, &left_width, &unused);
- free(test_text);
- width = MAX(left_width, right_width);
- tickoversize = width > 0.9 *
- ((double)(geom->axis[SCALE_ABSCISSA].data_max - geom->axis[SCALE_ABSCISSA].data_min))/bins;
+
for (i = 0; i < bins; i++)
{
- hist_draw_bar (cr, geom, h->gsl_hist, i, tick_format_string, tickscale, tickoversize);
+ hist_draw_bar (cr, geom, h->gsl_hist, i);
}
- free(tick_format_string);
histogram_write_legend (cr, geom, h->n, h->mean, h->stddev);
&& h->n != SYSMIS && h->mean != SYSMIS && h->stddev != SYSMIS)
{
/* Draw the normal curve */
- double d;
- double x_min, x_max, not_used;
- double abscissa_scale;
+ double x_min, x_max;
double ordinate_scale;
- double range;
+ double binwidth;
+ double x;
+
+ gsl_histogram_get_range (h->gsl_hist, 0, &x_min, &x_max);
+ binwidth = x_max - x_min;
- gsl_histogram_get_range (h->gsl_hist, 0, &x_min, ¬_used);
- range = not_used - x_min;
- gsl_histogram_get_range (h->gsl_hist, bins - 1, ¬_used, &x_max);
+ /* The integral over the histogram is binwidth * sum(bin_i), while the integral over the pdf is 1 */
+ /* Therefore the pdf has to be scaled accordingly such that the integrals are equal */
+ ordinate_scale = binwidth * gsl_histogram_sum(h->gsl_hist);
- abscissa_scale = (geom->axis[SCALE_ABSCISSA].data_max - geom->axis[SCALE_ABSCISSA].data_min) / (x_max - x_min);
- ordinate_scale = (geom->axis[SCALE_ORDINATE].data_max - geom->axis[SCALE_ORDINATE].data_min) /
- gsl_histogram_max_val (h->gsl_hist);
+ /* Clip normal curve to the rectangle formed by the axes. */
+ cairo_save (cr);
+ cairo_rectangle (cr, geom->axis[SCALE_ABSCISSA].data_min, geom->axis[SCALE_ORDINATE].data_min,
+ geom->axis[SCALE_ABSCISSA].data_max - geom->axis[SCALE_ABSCISSA].data_min,
+ geom->axis[SCALE_ORDINATE].data_max - geom->axis[SCALE_ORDINATE].data_min);
+ cairo_clip (cr);
cairo_move_to (cr, geom->axis[SCALE_ABSCISSA].data_min, geom->axis[SCALE_ORDINATE].data_min);
- for (d = geom->axis[SCALE_ABSCISSA].data_min;
- d <= geom->axis[SCALE_ABSCISSA].data_max;
- d += (geom->axis[SCALE_ABSCISSA].data_max - geom->axis[SCALE_ABSCISSA].data_min) / 100.0)
+ for (x = geom->axis[SCALE_ABSCISSA].min;
+ x <= geom->axis[SCALE_ABSCISSA].max;
+ x += (geom->axis[SCALE_ABSCISSA].max - geom->axis[SCALE_ABSCISSA].min) / 100.0)
{
- const double x = (d - geom->axis[SCALE_ABSCISSA].data_min) / abscissa_scale + x_min;
- const double y = h->n * range *
- gsl_ran_gaussian_pdf (x - h->mean, h->stddev);
-
- cairo_line_to (cr, d, geom->axis[SCALE_ORDINATE].data_min + y * ordinate_scale);
-
+ const double y = gsl_ran_gaussian_pdf (x - h->mean, h->stddev) * ordinate_scale;
+ /* Transform to drawing coordinates */
+ const double x_pos = (x - geom->axis[SCALE_ABSCISSA].min) * geom->axis[SCALE_ABSCISSA].scale + geom->axis[SCALE_ABSCISSA].data_min;
+ const double y_pos = (y - geom->axis[SCALE_ORDINATE].min) * geom->axis[SCALE_ORDINATE].scale + geom->axis[SCALE_ORDINATE].data_min;
+ cairo_line_to (cr, x_pos, y_pos);
}
cairo_stroke (cr);
+
+ cairo_restore (cr);
}
}