-/* 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 "decimal.h"
+#include <stdlib.h>
+
+#include "gl/xalloc.h"
+#include "gl/minmax.h"
+#include "gl/xvasprintf.h"
-/* Adjust tick to be a sensible value
+static const double standard_tick[] = {1, 2, 5, 10};
+
+/* 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)
+void
+chart_rounded_tick (double tick, struct decimal *result)
{
-
int i;
- double diff = DBL_MAX;
- double t = tick;
-
- static const double standard_ticks[] = {1, 2, 5, 10};
+ struct decimal ddif = {1, 1000};
+
+ /* Avoid arithmetic problems with very small values */
+ if (fabs (tick) < DBL_EPSILON)
+ {
+ result->ordinate = 0;
+ result->mantissa = 0;
+ return;
+ }
- const double factor = pow(10,ceil(log10(standard_ticks[0] / tick))) ;
+ struct decimal dt;
+ decimal_from_double (&dt, tick);
+
+ double expd = dec_log10 (&dt) - 1;
- for (i = 3 ; i >= 0 ; --i)
+ for (i = 0 ; i < 4 ; ++i)
{
- const double d = fabs( tick - standard_ticks[i] / factor ) ;
+ struct decimal candidate;
+ struct decimal delta;
- if ( d < diff )
+ decimal_init (&candidate, standard_tick[i], expd);
+
+ delta = dt;
+ decimal_subtract (&delta, &candidate);
+ delta.ordinate = llabs (delta.ordinate);
+
+ if (decimal_cmp (&delta, &ddif) < 0)
{
- diff = d;
- t = standard_ticks[i] / factor ;
+ ddif = delta;
+ *result = candidate;
}
}
+}
+
+/*
+ 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 highdbl, double lowdbl,
+ struct decimal *lower,
+ struct decimal *interval,
+ int *n_ticks)
+{
+ int i;
+ double fitness = DBL_MAX;
+ *n_ticks = 0;
+ struct decimal high;
+ struct decimal low;
+
+ assert (highdbl >= lowdbl);
+
+ decimal_from_double (&high, highdbl);
+ decimal_from_double (&low, lowdbl);
+
+ struct decimal diff = high;
+ decimal_subtract (&diff, &low);
+
+ double expd = dec_log10 (&diff) - 2;
+
+ /* Find the most pleasing interval */
+ for (i = 1; i < 4; ++i)
+ {
+ struct decimal clbound = low;
+ struct decimal cubound = high;
+ struct decimal candidate;
+ decimal_init (&candidate, standard_tick[i], expd);
+
+ decimal_divide (&clbound, &candidate);
+ int fl = decimal_floor (&clbound);
+ decimal_int_multiply (&candidate, fl);
+ clbound = candidate;
+
+
+ decimal_init (&candidate, standard_tick[i], expd);
+ decimal_divide (&cubound, &candidate);
+ int fu = decimal_ceil (&cubound);
+ decimal_int_multiply (&candidate, fu);
+
+ cubound = candidate;
- return t;
-
+ decimal_init (&candidate, standard_tick[i], expd);
+ decimal_subtract (&cubound, &clbound);
+ decimal_divide (&cubound, &candidate);
+
+
+ ord_t n_int = decimal_floor (&cubound);
+
+ /* We prefer to have between 5 and 10 tick marks on a scale */
+ double f = 1 - exp (-0.2 * fabs (n_int - 7.5) / 7.5);
+
+ if (f < fitness)
+ {
+ fitness = f;
+ *lower = clbound;
+ *interval = candidate;
+ *n_ticks = n_int;
+ }
+ }
}
+/*
+ * Compute the optimum format string and the scaling
+ * for the tick drawing on a chart axis
+ * Input: max: the maximum value of the range
+ * min: the minimum value of the range
+ * 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(95359943.3,34434.9,8,&scale);
+ * printf(fs,value*scale);
+ * free(fs);
+ */
+char *
+chart_get_ticks_format (const double max, const double min,
+ const unsigned int nticks, double *scale)
+{
+ assert(max > min);
+ double interval = (max - min)/nticks;
+ double logmax = log10(fmax(fabs(max),fabs(min)));
+ 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)(fabs(logintv))+1);
+ logshift = 0;
+ format_string = xasprintf("%%.%dlf",nrdecs);
+ }
+ else if (logmax > 0.0) /*logintv is > 0*/
+ {
+ if (logintv < 5.0)
+ {
+ logshift = 0; /* No scientific format */
+ nrdecs = 0;
+ format_string = xstrdup("%.0lf");
+ }
+ else
+ {
+ logshift = (int)logmax;
+ nrdecs = MIN(6,(int)(logmax-logintv)+1);
+ format_string = xasprintf("%%.%dlf∙10<sup>%d</sup>",nrdecs,logshift);
+ }
+ }
+ else /* logmax and logintv are < 0 */
+ {
+ if (logmax > -4.0)
+ {
+ logshift = 0; /* No scientific format */
+ nrdecs = (int)(-logintv) + 1;
+ format_string = xasprintf("%%.%dlf",nrdecs);
+ }
+ else
+ {
+ logshift = (int)logmax-1;
+ nrdecs = MIN(6,(int)(logmax-logintv)+1);
+ format_string = xasprintf("%%.%dlf∙10<sup>%d</sup>",nrdecs,logshift);
+ }
+ }
+ *scale = pow(10.0,-(double)logshift);
+ return format_string;
+}
projects / pspp / blobdiff