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/*--------------------------------------------------------------------
* $Id: grdhisteq.c,v 1.4 2001/04/11 19:58:09 pwessel Exp $
*
* Copyright (c) 1991-2001 by P. Wessel and W. H. F. Smith
* See COPYING file for copying and redistribution conditions.
*
* 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; version 2 of the License.
*
* 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.
*
* Contact info: gmt.soest.hawaii.edu
*--------------------------------------------------------------------*/
/*
* read a grdfile and find the values which divide its range
* into n_cell number of quantiles.
*
* Author: W.H.F. Smith
* Date: 31 May 1990
*
* Modified: 12 June, 1990 by whf smith, adding [-Q] option for
* quadratic scaling. Some rgb color systems consider that
* if black = (0,0,0) and white = (1,1,1) or (255,255,255),
* then a neutral gray "halfway" between black and while should
* be set to gray = (0.75,0.75,0.75) or (191,191,191). If so,
* let 0 <= x <= 1 be the desired gradation between black and
* white (the intensity factor used by the coloring program.
* Then the gray tone level 0 <= y <= 1 is given by:
* y = 2*x - x**2.
* Using the -Q option will find the data values which divide
* the data range into <n_cells> values of y; default linear
* scaling will find the values for <n_cells> divisions of x.
*
* Updated to v2.0 15-May-1991 Paul Wessel
* Updated to v3.1 14-Jun-1998 Paul Wessel
* Updated to v3.3.5 14-Jun-2000 Paul Wessel
* Version: 3.4
*/
#include "gmt.h"
struct INDEXED_DATA {
float x;
int i;
} *indexed_data;
struct CELL {
float low;
float high;
} *cell;
float *data, data_min, data_max;
float get_cell(float x);
double qsnorm(double p), norm = 0.0;
int last_cell, n_cells = 0, n_cells_m1 = 0;
int i, j, nxy;
int compare_indexed_floats(const void *point_1, const void *point_2);
int compare_indices(const void *point_1, const void *point_2);
void do_usual (char *infile, char *outfile, int n_cells, int quadratic, int dump_intervals, int argc, char **argv);
void do_gaussian (char *infile, char *outfile, int argc, char **argv);
main (int argc, char **argv)
{
int i;
int dump = FALSE, error = FALSE, quadratic = FALSE, gaussian = FALSE;
char *infile = CNULL, *outfile = CNULL;
argc = GMT_begin (argc, argv);
for (i = 1; i < argc; i++) {
if (argv[i][0] == '-') {
switch (argv[i][1]) {
/* Common parameters */
case 'V':
case '\0':
error += GMT_get_common_args (argv[i], 0, 0, 0, 0);
break;
/* Supplemental parameters */
case 'C':
n_cells = atoi(&argv[i][2]);
break;
case 'D':
dump = TRUE;
break;
case 'G':
outfile = &argv[i][2];
break;
case 'N':
gaussian = TRUE;
if (argv[i][2]) norm = atof (&argv[i][2]);
break;
case 'Q':
quadratic = TRUE;
break;
default:
error = TRUE;
GMT_default_error (argv[i][1]);
break;
}
}
else
infile = argv[i];
}
if (argc == 1 || GMT_quick) {
fprintf (stderr,"grdhisteq %s - Histogram equalization for grdfiles\n\n", GMT_VERSION);
fprintf (stderr, "usage: grdhisteq <infile> -G<outfile> [-C<n_cells> -D -N[<norm>] -Q -V]\n");
if (GMT_quick) exit (EXIT_FAILURE);
fprintf (stderr, "\t-C<n_cells> sets how many cells (divisions) of data range to make.\n");
fprintf (stderr, "\t-D dump level information to stdout\n");
fprintf (stderr, "\t-G<outfile> will create an equalized output grdfile.\n");
fprintf (stderr, "\t-N use with -G to make an output grdfile with standard normal scores.\n");
fprintf (stderr, "\t Append <norm> to normalize the scores to <-1,+1>\n");
fprintf (stderr, "\t-Q to use quadratic intensity scaling. [Default is linear]\n");
GMT_explain_option ('V');
exit (EXIT_FAILURE);
}
if (!infile) {
fprintf (stderr, "%s: GMT SYNTAX ERROR: Must specify input file\n", GMT_program);
error++;
}
if (gaussian && !outfile) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -N option: Must also specify output file with -G\n", GMT_program);
error++;
}
if (!gaussian && n_cells <= 0) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -C option: n_cells must be positive\n", GMT_program);
error++;
}
if (error) exit (EXIT_FAILURE);
GMT_put_history (argc, argv); /* Update .gmtcommands */
if (!strcmp (infile, "=")) {
fprintf (stderr, "%s: Piping of input grdfile not supported!\n", GMT_program);
exit (EXIT_FAILURE);
}
if (gaussian)
do_gaussian (infile, outfile, argc, argv);
else
do_usual (infile, outfile, n_cells, quadratic, dump, argc, argv);
GMT_end (argc, argv);
}
void do_usual (char *infile, char *outfile, int n_cells, int quadratic, int dump_intervals, int argc, char **argv)
{
double delta_cell, target;
struct GRD_HEADER header;
int nxy, nxy_0, current_cell;
char format[BUFSIZ];
sprintf (format, "%s\t%s\t%%d\n\0", gmtdefs.d_format, gmtdefs.d_format);
if (GMT_read_grd_info (infile, &header)) {
fprintf (stderr, "%s: GMT SYNTAX ERROR: File %s not found\n", GMT_program, infile);
exit (EXIT_FAILURE);
}
GMT_grd_init (&header, argc, argv, TRUE);
nxy_0 = header.nx * header.ny;
data = (float *) GMT_memory (VNULL, (size_t)nxy_0, sizeof (float), GMT_program);
GMT_read_grd (infile, &header, data, 0.0, 0.0, 0.0, 0.0, GMT_pad, FALSE);
cell = (struct CELL *) GMT_memory (VNULL, (size_t)n_cells, sizeof(struct CELL), GMT_program);
/* Sort the data and find the division points: */
qsort ((void *)data, (size_t)nxy_0, sizeof(float), GMT_comp_float_asc);
nxy = nxy_0;
while (nxy > 0 && GMT_is_fnan (data[nxy-1])) nxy--; /* Only deal with real numbers */
data_min = data[0];
data_max = data[nxy - 1];
last_cell = n_cells/2;
n_cells_m1 = n_cells - 1;
current_cell = 0;
i = 0;
delta_cell = ((double)nxy) / ((double)n_cells);
while (current_cell < n_cells) {
if (current_cell == (n_cells - 1) ) {
j = nxy - 1;
}
else if (quadratic) { /* Use y = 2x - x**2 scaling */
target = ( (double) (current_cell + 1) ) / ( (double) n_cells);
j = (int)floor(nxy * (1.0 - sqrt(1.0 - target)));
}
else { /* Use simple linear scale */
j = (int)(floor( (current_cell + 1) * delta_cell)) - 1;
}
cell[current_cell].low = data[i];
cell[current_cell].high = data[j];
if (dump_intervals) fprintf (GMT_stdout, format, data[i], data[j], current_cell);
i = j;
current_cell++;
}
if (outfile) {
GMT_read_grd (infile, &header, data, 0.0, 0.0, 0.0, 0.0, GMT_pad, FALSE);
for (i = 0; i < nxy_0; i++) data[i] = (GMT_is_fnan (data[i])) ? GMT_f_NaN : get_cell (data[i]);
GMT_write_grd (outfile, &header, data, 0.0, 0.0, 0.0, 0.0, GMT_pad, FALSE);
}
GMT_free ((void *) data);
GMT_free ((void *) cell);
}
float get_cell(float x)
{
int low, high, i;
low = 0;
high = n_cells_m1;
i = last_cell;
do {
if (cell[i].low <= x && cell[i].high >= x) {
last_cell = i;
return ( (float)i);
}
else if (cell[low].low <= x && cell[low].high >= x) {
return ( (float)low);
}
else if (cell[high].low <= x && cell[high].high >= x) {
return ( (float)high);
}
else if (cell[i].low > x) {
high = i;
i = (low + high) / 2;
}
else if (cell[i].high < x) {
low = i;
i = (low + high) / 2;
}
} while (TRUE);
}
void do_gaussian (char *infile, char *outfile, int argc, char **argv)
{
int i, j, nxy_0;
double dnxy;
struct GRD_HEADER header;
if (GMT_read_grd_info (infile, &header)) {
fprintf (stderr, "%s: GMT SYNTAX ERROR: File %s not found\n", GMT_program, infile);
exit (EXIT_FAILURE);
}
GMT_grd_init (&header, argc, argv, TRUE);
nxy_0 = header.nx * header.ny;
data = (float *) GMT_memory (VNULL, (size_t)nxy_0, sizeof (float), GMT_program);
GMT_read_grd (infile, &header, data, 0.0, 0.0, 0.0, 0.0, GMT_pad, FALSE);
indexed_data = (struct INDEXED_DATA *) GMT_memory (VNULL, (size_t)nxy_0, sizeof (struct INDEXED_DATA), GMT_program);
for (i = j = 0, nxy = nxy_0; i < nxy_0; i++) {
if (GMT_is_fnan (data[i])) { /* Put NaNs in the back */
nxy--;
indexed_data[nxy].i = i;
indexed_data[nxy].x = data[i];
}
else {
indexed_data[j].i = i;
indexed_data[j].x = data[i];
j++;
}
}
/* Sort on data value */
qsort ((void *)indexed_data, (size_t)nxy, sizeof(struct INDEXED_DATA), compare_indexed_floats);
dnxy = 1.0 / (nxy + 1);
if (norm != 0.0) norm /= fabs (qsnorm ((double)dnxy)); /* Normalize by abs(max score) */
for (i = 0; i < nxy; i++) {
indexed_data[i].x = (float)qsnorm ((double)((i + 1) * dnxy));
if (norm != 0.0) indexed_data[i].x *= (float)norm;
}
/* Sort on data index */
qsort ((void *)indexed_data, (size_t)nxy_0, sizeof(struct INDEXED_DATA), compare_indices);
for (i = 0; i < nxy_0; i++) data[i] = indexed_data[i].x;
GMT_write_grd (outfile, &header, data, 0.0, 0.0, 0.0, 0.0, GMT_pad, FALSE);
GMT_free ((void *) indexed_data);
GMT_free ((void *) data);
}
int compare_indexed_floats(const void *point_1, const void *point_2)
{
if ( ((struct INDEXED_DATA *)point_1)->x < ((struct INDEXED_DATA *)point_2)->x )
return (-1);
else if ( ((struct INDEXED_DATA *)point_1)->x > ((struct INDEXED_DATA *)point_2)->x )
return (1);
else
return (0);
}
int compare_indices(const void *point_1, const void *point_2)
{
if ( ((struct INDEXED_DATA *)point_1)->i < ((struct INDEXED_DATA *)point_2)->i )
return (-1);
else if ( ((struct INDEXED_DATA *)point_1)->i > ((struct INDEXED_DATA *)point_2)->i )
return (1);
else
return (0);
}
/* double qsnorm(p)
* double p;
*
* Function to invert the cumulative normal probability
* function. If z is a standardized normal random deviate,
* and Q(z) = p is the cumulative Gaussian probability
* function, then z = qsnorm(p).
*
* Note that 0.0 < p < 1.0. Data values outside this range
* will return +/- a large number (1.0e6).
* To compute p from a sample of data to test for Normalcy,
* sort the N samples into non-decreasing order, label them
* i=[1, N], and then compute p = i/(N+1).
*
* Author: Walter H. F. Smith
* Date: 19 February, 1991.
*
* Based on a Fortran subroutine by R. L. Parker. I had been
* using IMSL library routine DNORIN(DX) to do what qsnorm(p)
* does, when I was at the Lamont-Doherty Geological Observatory
* which had a site license for IMSL. I now need to invert the
* gaussian CDF without calling IMSL; hence, this routine.
*
*/
double qsnorm(double p)
{
double t, z;
if (p <= 0.0) {
fprintf(stderr,"%s: qsnorm: Bad probability.\n", GMT_program);
return(-1.0e6);
}
else if (p >= 1.0) {
fprintf(stderr,"%s: qsnorm: Bad probability.\n", GMT_program);
return(1.0e6);
}
else if (p == 0.5) {
return(0.0);
}
else if (p > 0.5) {
t = sqrt(-2.0 * log(1.0 - p) );
z = t - (2.515517 +t*(0.802853 +t*0.010328))/
(1.0 + t*(1.432788 + t*(0.189269+ t*0.001308)));
return(z);
}
else {
t = sqrt(-2.0 * log(p) );
z = t - (2.515517 +t*(0.802853 +t*0.010328))/
(1.0 + t*(1.432788 + t*(0.189269+ t*0.001308)));
return(-z);
}
}
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