-/* PSPP - computes sample statistics.
- Copyright (C) 2004 Free Software Foundation, Inc.
+/* PSPP - a program for statistical analysis.
+ Copyright (C) 2004, 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 the Free Software Foundation; either version 2 of the
- License, or (at your option) any later version.
+ 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
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
- This program is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software
- Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
- 02110-1301, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
#include <math.h>
#include <float.h>
+#include <assert.h>
#include "chart-geometry.h"
+#include <stdlib.h>
-/* Adjust tick to be a sensible value
- ie: ... 0.1,0.2,0.5, 1,2,5, 10,20,50 ... */
-double
-chart_rounded_tick(double tick)
-{
+#include "gl/xalloc.h"
+#include "gl/minmax.h"
+#include "gl/xvasprintf.h"
+
+#include "gettext.h"
+#define _(msgid) gettext (msgid)
+
+static const double standard_tick[] = {1, 2, 5, 10};
+
+/*
+ Find a set {LOWER, INTERVAL, N_TICKS} such that:
+
+ LOWER <= LOWDBL,
+ LOWER + INTERVAL > LOWDBL,
+ LOWER + N_TICKS * INTERVAL < HIGHDBL
+ LOWER + (N_TICKS + 1) * INTERVAL >= HIGHDBL
+
+ INTERVAL = X * 10^N
+ where: N is integer
+ and X is an element of {1, 2, 5}
+
+ In other words:
+
+ INTERVAL
+ > <
+ |....+....+....+. .+....|
+ LOWER 1 2 3 N_TICKS
+ ^LOWDBL ^HIGHDBL
+*/
+void
+chart_get_scale (double high, double low,
+ double *lower, double *interval,
+ int *n_ticks)
+{
int i;
+ double fitness = DBL_MAX;
+ double logrange;
+ *n_ticks = 0;
- double diff = DBL_MAX;
- double t = tick;
-
- static const double standard_ticks[] = {1, 2, 5, 10};
+ assert (high >= low);
- const double factor = pow(10,ceil(log10(standard_ticks[0] / tick))) ;
+ if ((high - low) < 10 * DBL_MIN) {
+ *n_ticks = 0;
+ *lower = low;
+ *interval = 0.0;
+ return;
+ }
- for (i = 3 ; i >= 0 ; --i)
+ logrange = floor(log10(high-low));
+
+ /* Find the most pleasing interval */
+ for (i = 1; i < 4; ++i)
{
- const double d = fabs( tick - standard_ticks[i] / factor ) ;
+ double cinterval = standard_tick[i] * pow(10.0,logrange-1);
+ double clower = floor(low/cinterval) * cinterval;
+ int cnticks = ceil((high - clower) / cinterval)-1;
+ double cfitness = fabs(7.5 - cnticks);
- if ( d < diff )
- {
- diff = d;
- t = standard_ticks[i] / factor ;
- }
+ if (cfitness < fitness) {
+ fitness = cfitness;
+ *lower = clower;
+ *interval = cinterval;
+ *n_ticks = cnticks;
+ }
}
+}
+
+/*
+ Generate a format string which can be passed to printf like functions,
+ which will produce a string in scientific notation representing a real
+ number. N_DECIMALS is the number of decimal places EXPONENT is the
+ value of the exponent.
+*/
+static inline char *
+gen_pango_markup_scientific_format_string (int n_decimals, int exponent)
+{
+ /* TRANSLATORS: This is a format string which, when presented to
+ printf like functions, will create a pango markup string to
+ display real number in scientific notation.
+
+ In its untranslated form, it will display similar to "1.23 x 10^4". You
+ can leave it untranslated if this is how scientific notation is usually
+ presented in your language.
+
+ Some locales (such as German) prefer the centered dot rather than the
+ multiplication sign between the mantissa an exponent. In which
+ case, you can change "#215;" to "#8901;" or other unicode code
+ point as appropriate.
+
+ The . in this string does not and should not be changed, since
+ that is taken care of by the stdc library.
- return t;
-
+ For information on Pango markup, see
+ http://developer.gnome.org/pango/stable/PangoMarkupFormat.html
+
+ For tables of unicode code points, see http://unicode.org/charts
+ */
+ return xasprintf(_("%%.%dlf×10<sup>%d</sup>"), n_decimals, exponent);
}
+/*
+ * Compute the optimum format string and the scaling
+ * for the tick drawing on a chart axis
+ * Input: lower: the lowest tick
+ * interval:the interval between the ticks
+ * nticks: the number of tick intervals (bins) on the axis
+ * Return: fs: format string for printf to print the tick value
+ * scale: scaling factor for the tick value
+ * The format string has to be freed after usage.
+ * An example format string and scalefactor:
+ * Non Scientific: "%.3lf", scale=1.00
+ * Scientific: "%.2lfe3", scale = 0.001
+ * Usage example:
+ * fs = chart_get_ticks_format(-0.7,0.1,8,&scale);
+ * printf(fs,value*scale);
+ * free(fs);
+ */
+char *
+chart_get_ticks_format (const double lower, const double interval,
+ const unsigned int nticks, double *scale)
+{
+ double logmax = log10(fmax(fabs(lower + (nticks+1)*interval),fabs(lower)));
+ double logintv = log10(interval);
+ int logshift = 0;
+ char *format_string = NULL;
+ int nrdecs = 0;
+
+ if (logmax > 0.0 && logintv < 0.0)
+ {
+ nrdecs = MIN(6,(int)(ceil(fabs(logintv))));
+ logshift = 0;
+ if (logmax < 12.0)
+ format_string = xasprintf("%%.%dlf",nrdecs);
+ else
+ format_string = xasprintf("%%lg");
+ }
+ else if (logmax > 0.0) /*logintv is > 0*/
+ {
+ if (logintv < 5.0 && logmax < 10.0)
+ {
+ logshift = 0; /* No scientific format */
+ nrdecs = 0;
+ format_string = xstrdup("%.0lf");
+ }
+ else
+ {
+ logshift = (int)logmax;
+ /* Possible intervals are 0.2Ex, 0.5Ex, 1.0Ex */
+ /* log10(0.2E9) = 8.30, log10(0.5E9) = 8.69, log10(1.0E9) = 9 */
+ /* 0.2 and 0.5 need one decimal more. For stability subtract 0.1 */
+ nrdecs = MIN(8,(int)(ceil(logshift-logintv-0.1)));
+ format_string = gen_pango_markup_scientific_format_string (nrdecs, logshift);
+ }
+ }
+ else /* logmax and logintv are < 0 */
+ {
+ if (logmax > -3.0)
+ {
+ logshift = 0; /* No scientific format */
+ nrdecs = MIN(8,(int)(ceil(-logintv)));
+ format_string = xasprintf("%%.%dlf",nrdecs);
+ }
+ else
+ {
+ logshift = (int)logmax-1;
+ nrdecs = MIN(8,(int)(ceil(logshift-logintv-0.1)));
+ format_string = gen_pango_markup_scientific_format_string (nrdecs, logshift);
+ }
+ }
+ *scale = pow(10.0,-(double)logshift);
+ return format_string;
+}