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/*--------------------------------------------------------------------
* The GMT-system: @(#)nearneighbor.c 2.70 10/29/99
*
* Copyright (c) 1991-1999 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: www.soest.hawaii.edu/gmt
*--------------------------------------------------------------------*/
/*
* Based on a specified grid size, nearneighbor reads an xyz file and
* determines the nearest points to each node in sectors. The default
* looks for the nearest point for each quadrant. The points must also
* be within a maximum search-radius from the node. For the nodes that
* have a full set of nearest neighbors, a weighted average value is
* computed. New feature is full support for boundary conditions so
* that geographic or periodic conditions are explicitly dealt with
* in the sense that a data point may wrap around to serve as a
* constraint on the other side of the periodic boundary.
*
* Author: Paul Wessel
* Date: 02-JUN-1999
* Version: 3.3
*/
#include "gmt.h"
#include "gmt_boundcond.h"
float *grd;
struct NODE { /* Structure with point id and distance pairs for all sectors */
float *distance; /* Distance of nearest datapoint to this node per sector */
int *datum; /* Point id of this data point */
} **grid_node;
struct POINT { /* Structure with input data constraints */
float x, y, z, w;
} *point;
struct NODE *add_new_node(int n);
void assign_node (struct NODE **node, int n_sector, int sector, double distance, int id);
main (int argc, char **argv)
{
int i, j, k, ij, i0, j0, *di, dj, n_sectors = 4, sector, n, n_alloc = 5 * GMT_CHUNK, n_fields, nx_2;
int ix, iy, n_set, n_almost, n_none, n_files = 0, n_args, fno, one_or_zero, n_expected_fields, pad[4], distance_flag = 0;
int max_di, actual_max_di, ii, jj, n_req;
BOOLEAN go, error = FALSE, done = FALSE, first = TRUE, nofile = TRUE;
BOOLEAN set_empty = FALSE, weighted = FALSE, skip, wrap_180;
double radius = 0.0, weight, weight_sum, *x0, *y0, dx, dy, delta, distance, factor;
double *in, *shrink, km_pr_deg, x_left, x_right, y_top, y_bottom, offset, xinc2, yinc2, idx, idy;
double half_y_width, y_width, half_x_width, x_width;
float empty = 0.0;
char *outfile = CNULL, line[BUFSIZ];
FILE *fp = NULL;
struct GRD_HEADER header;
struct GMT_EDGEINFO edgeinfo;
argc = GMT_begin (argc, argv);
GMT_boundcond_init (&edgeinfo);
GMT_grd_init (&header, argc, argv, FALSE);
pad[0] = pad[1] = pad[2] = pad[3] = 0;
for (i = 1; i < argc; i++) {
if (argv[i][0] == '-') {
switch (argv[i][1]) {
/* Common parameters */
case 'H':
case 'R':
case 'V':
case ':':
case '\0':
error += GMT_get_common_args (argv[i], &header.x_min, &header.x_max, &header.y_min, &header.y_max);
break;
/* Supplemental parameters */
case 'b': /* Input triplets [quadruplets] are binary, not ascii */
error += GMT_io_selection (&argv[i][2]);
break;
case 'I':
GMT_getinc (&argv[i][2], &header.x_inc, &header.y_inc);
break;
case 'E':
if (!argv[i][2]) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -E option: Must specify value or NaN\n", GMT_program);
error++;
}
else
empty = (argv[i][2] == 'N' || argv[i][2] == 'n') ? GMT_f_NaN : (float)atof (&argv[i][2]);
set_empty = TRUE;
break;
case 'F':
header.node_offset = TRUE;
break;
case 'G':
outfile = &argv[i][2];
break;
case 'L':
error += GMT_boundcond_parse (&edgeinfo, &argv[i][2]);
break;
case 'N':
n_sectors = atoi (&argv[i][2]);
break;
case 'S':
GMT_getinc (&argv[i][2], &radius, &radius);
if (argv[i][strlen(argv[i])-1] == 'k') distance_flag = 1;
if (argv[i][strlen(argv[i])-1] == 'K') distance_flag = 2;
break;
case 'W':
weighted = TRUE;
break;
default:
error = TRUE;
GMT_default_error (argv[i][1]);
break;
}
}
else
n_files++;
}
if (argc == 1 || GMT_quick) {
fprintf (stderr, "nearneighbor %s - A \"Nearest neighbor\" gridding algorithm\n\n", GMT_VERSION);
fprintf(stderr, "usage: nearneighbor [xyzfile(s)] -G<out_grdfile> -I<dx>[m|c][/<dy>[m|c]]\n");
fprintf(stderr, " -N<sectors> -R<west/east/south/north> -S<radius>[m|c|k|K] [-E<empty>] [-F]\n");
fprintf(stderr, " [-H ] [-L<flags>] [-V ] [-W] [-:] [-bi[s][<n>]]\n\n");
if (GMT_quick) exit (EXIT_FAILURE);
fprintf(stderr, " -G name of output grid.\n");
fprintf(stderr, " -I sets the grid spacing for the grid. Append m for minutes, c for seconds.\n");
fprintf(stderr, " -N sets number of sectors. Default is quadrant search [4].\n");
GMT_explain_option ('R');
fprintf(stderr, " -S sets search radius in -R, -I units; append m or c for minutes or seconds.\n");
fprintf(stderr, " Append k for km (implies -R,-I in degrees), use flat Earth approximation.\n");
fprintf(stderr, " Append K for km (implies -R,-I in degrees), use great circle distances.\n");
fprintf(stderr, " \n");
fprintf(stderr, "\n\tOPTIONS:\n");
fprintf(stderr, " -E value to use for empty nodes [Default is NaN].\n");
fprintf(stderr, " -F Force pixel registration [Default is gridline registration].\n");
GMT_explain_option ('H');
fprintf(stderr, " -L sets boundary conditions. <flags> can be either\n");
fprintf(stderr, " g for geographic boundary conditions, or one or both of\n");
fprintf(stderr, " x for periodic boundary conditions on x\n");
fprintf(stderr, " y for periodic boundary conditions on y\n");
GMT_explain_option ('V');
fprintf(stderr, " -W input file has observation weights in 4th column.\n");
GMT_explain_option (':');
GMT_explain_option ('i');
GMT_explain_option ('n');
fprintf(stderr, " Default is 3 (or 4 if -W is set) columns\n");
GMT_explain_option ('.');
exit (EXIT_FAILURE);
}
if (!project_info.region_supplied) {
fprintf (stderr, "%s: GMT SYNTAX ERROR: Must specify -R option\n", GMT_program);
error++;
}
if (!outfile) {
fprintf (stderr, "%s: GMT SYNTAX ERROR option -G: Must specify output file\n", GMT_program);
error++;
}
if (n_sectors <= 0) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -N option: Must specify a positive number of sectors\n", GMT_program);
error++;
}
if (radius <= 0.0) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -S option: Must specify a positive search radius\n", GMT_program);
error++;
}
if (header.x_inc <= 0.0 || header.y_inc <= 0.0) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -I option. Must specify positive increment(s)\n", GMT_program);
error++;
}
if (GMT_io.binary[0] && gmtdefs.io_header) {
fprintf (stderr, "%s: GMT SYNTAX ERROR. Binary input data cannot have header -H\n", GMT_program);
error++;
}
n_req = (weighted) ? 4 : 3;
if (GMT_io.binary[0] && GMT_io.ncol[0] == 0) GMT_io.ncol[0] = n_req;
if (GMT_io.binary[0] && n_req > GMT_io.ncol[0]) {
fprintf (stderr, "%s: GMT SYNTAX ERROR. binary input data must have at least %d columns\n", GMT_program, n_req);
error++;
}
if (error) exit (EXIT_FAILURE);
GMT_put_history (argc, argv); /* Update .gmtcommands */
if (GMT_io.binary[0] && gmtdefs.verbose) {
char *type[2] = {"double", "single"};
fprintf (stderr, "%s: Expects %d-column %s-precision binary data\n", GMT_program, GMT_io.ncol[0], type[GMT_io.single_precision[0]]);
}
GMT_grd_RI_verify (&header);
n_expected_fields = (GMT_io.binary[0]) ? GMT_io.ncol[0] : BUFSIZ;
ix = (gmtdefs.xy_toggle); iy = 1 - ix;
if (n_files > 0)
nofile = FALSE;
else
n_files = 1;
n_args = (argc > 1) ? argc : 2;
if (header.node_offset) {
one_or_zero = 0;
offset = 0.0;
xinc2 = 0.5 * header.x_inc;
yinc2 = 0.5 * header.y_inc;
}
else {
one_or_zero = 1;
offset = 0.5;
xinc2 = yinc2 = 0.0;
}
idx = 1.0 / header.x_inc;
idy = 1.0 / header.y_inc;
header.nx = irint ( (header.x_max - header.x_min) * idx) + one_or_zero;
header.ny = irint ( (header.y_max - header.y_min) * idy) + one_or_zero;
GMT_boundcond_param_prep (&header, &edgeinfo);
if (gmtdefs.verbose) fprintf (stderr, "%s: Grid dimensions are nx = %d, ny = %d\n", GMT_program,
header.nx, header.ny);
grid_node = (struct NODE **) GMT_memory (VNULL, (size_t)(header.nx * header.ny), sizeof (struct NODE *), GMT_program);
point = (struct POINT *) GMT_memory (VNULL, (size_t)n_alloc, sizeof (struct POINT), GMT_program);
di = (int *) GMT_memory (VNULL, (size_t)header.ny, sizeof (int), GMT_program);
shrink = (double *) GMT_memory (VNULL, (size_t)header.ny, sizeof (double), GMT_program);
x0 = (double *) GMT_memory (VNULL, (size_t)header.nx, sizeof (double), GMT_program);
y0 = (double *) GMT_memory (VNULL, (size_t)header.ny, sizeof (double), GMT_program);
for (i = 0; i < header.nx; i++) x0[i] = header.x_min + i * header.x_inc + xinc2;
for (j = 0; j < header.ny; j++) y0[j] = header.y_max - j * header.y_inc - yinc2;
if (distance_flag) { /* Input data is geographical */
km_pr_deg = 0.001 * 2.0 * M_PI * gmtdefs.ellipse[gmtdefs.ellipsoid].eq_radius / 360.0;
max_di = (int) (ceil (header.nx / 2.0) + 0.1);
actual_max_di = 0;
for (j = 0; j < header.ny; j++) {
shrink[j] = cosd (y0[j]);
di[j] = (fabs (y0[j]) == 90.0) ? max_di : (int)(ceil (radius / (km_pr_deg * header.x_inc * shrink[j])) + 0.1);
if (di[j] > max_di) di[j] = max_di;
if (di[j] > actual_max_di) actual_max_di = di[j];
}
dj = (int) (ceil (radius / (km_pr_deg * header.y_inc)) + 0.1);
}
else { /* Plain Cartesian data */
max_di = (int) (ceil (radius * idx) + 0.1);
for (j = 0; j < header.ny; j++) di[j] = max_di;
dj = (int) (ceil (radius * idy) + 0.1);
actual_max_di = max_di;
}
factor = n_sectors / (2.0 * M_PI);
x_left = header.x_min - actual_max_di * header.x_inc; x_right = header.x_max + actual_max_di * header.x_inc;
y_top = header.y_max + dj * header.y_inc; y_bottom = header.y_min - dj * header.y_inc;
x_width = header.x_max - header.x_min; y_width = header.y_max - header.y_min;
half_x_width = 0.5 * x_width; half_y_width = 0.5 * y_width;
nx_2 = edgeinfo.nxp / 2;
n = 0;
for (fno = 1; !done && fno < n_args; fno++) { /* Loop over input files, if any */
if (!nofile && argv[fno][0] == '-') continue;
if (nofile) { /* Just read standard input */
fp = GMT_stdin;
done = TRUE;
#ifdef SET_IO_MODE
GMT_setmode (0);
#endif
}
else if ((fp = GMT_fopen (argv[fno], GMT_io.r_mode)) == NULL) {
fprintf (stderr, "%s: Cannot open file %s\n", GMT_program, argv[fno]);
continue;
}
if (!nofile && gmtdefs.verbose) fprintf (stderr, "%s: Working on file %s\n", GMT_program, argv[fno]);
if (gmtdefs.io_header) {
for (i = 0; i < gmtdefs.n_header_recs; i++) {
fgets (line, BUFSIZ, fp);
if (first) printf ("%s", line);
}
first = FALSE;
}
n_fields = GMT_input (fp, &n_expected_fields, &in);
while (! (GMT_io.status & GMT_IO_EOF)) { /* Not yet EOF */
skip = FALSE;
if (GMT_io.status & GMT_IO_MISMATCH) {
fprintf (stderr, "%s: Mismatch between actual (%d) and expected (%d) fields near line %d\n", GMT_program, n_fields, n_expected_fields, n);
exit (EXIT_FAILURE);
}
if (in[ix] < x_left || in[ix] > x_right) skip = TRUE;
if (in[iy] < y_bottom || in[iy] > y_top) skip = TRUE;
if (!skip) {
point[n].x = (float)in[ix];
point[n].y = (float)in[iy];
point[n].z = (float)in[2];
if (weighted) point[n].w = (float)in[3];
/* Find indeces of the node closest to this data point */
i0 = (int)floor (((in[ix] - header.x_min) * idx) + offset);
j0 = (int)floor (((header.y_max - in[iy]) * idy) + offset);
/* Loop over all nodes within radius of this node */
for (j = j0 - dj; j <= (j0 + dj); j++) {
wrap_180 = FALSE;
if (j < 0) { /* Depending on BC's we wrap around or skip */
if (edgeinfo.gn) { /* N Polar condition */
jj = abs (j) - header.node_offset;
wrap_180 = TRUE;
}
else if (edgeinfo.nyp) { /* Periodic in y */
jj = j + edgeinfo.nyp;
}
else
continue;
}
else if (j >= header.ny) { /* Depending on BC's we wrap around or skip */
if (edgeinfo.gs) { /* S Polar condition */
jj = j - 2 + header.node_offset;
wrap_180 = TRUE;
}
else if (edgeinfo.nyp) { /* Periodic in y */
jj = j - edgeinfo.nyp;
}
else
continue;
}
else
jj = j;
for (i = i0 - di[jj]; i <= (i0 + di[jj]); i++) {
if (i < 0) { /* Depending on BC's we wrap around or skip */
if (edgeinfo.nxp) { /* Periodic in x */
ii = abs (i) - header.node_offset;
}
else
continue;
}
else if (i >= header.nx) { /* Depending on BC's we wrap around or skip */
if (edgeinfo.nxp) { /* Periodic in x */
ii = i - edgeinfo.nxp;
}
else
continue;
}
else
ii = i;
if (wrap_180) ii = (ii + nx_2) % edgeinfo.nxp;
k = jj * header.nx + ii;
dx = in[ix] - x0[ii]; dy = in[iy] - y0[jj];
/* Check for wrap-around in x or y */
if (edgeinfo.nxp && fabs (dx) > half_x_width) dx -= copysign (x_width, dx);
if (edgeinfo.nyp && fabs (dy) > half_y_width) dy -= copysign (y_width, dy);
switch (distance_flag) { /* Take different action depending on how we want distances calculated */
case 0: /* Cartesian distance */
distance = hypot (dx, dy);
break;
case 1: /* Flat Earth Approximation */
distance = km_pr_deg * hypot (dx * shrink[jj], dy);
break;
case 2: /* Full spherical calculation */
distance = km_pr_deg * GMT_great_circle_dist (x0[ii], y0[jj], in[ix], in[iy]);
break;
default:
break;
}
if (distance > radius) continue;
sector = ((int)((d_atan2 (dy, dx) + M_PI) * factor)) % n_sectors;
assign_node (&grid_node[k], n_sectors, sector, distance, n);
if (edgeinfo.nxp && ii == 0) { /* Must replicate to redundant column */
assign_node (&grid_node[k+header.nx-1], n_sectors, sector, distance, n);
if (edgeinfo.nyp && jj == 0) /* Must replicate to redundant row */
assign_node (&grid_node[header.nx-1], n_sectors, sector, distance, n);
}
if (edgeinfo.nyp && jj == 0) /* Must replicate to redundant row */
assign_node (&grid_node[ii], n_sectors, sector, distance, n);
}
}
n++;
if (n == n_alloc) {
n_alloc += GMT_CHUNK;
point = (struct POINT *) GMT_memory ((void *)point, (size_t)n_alloc, sizeof (struct POINT), GMT_program);
}
}
n_fields = GMT_input (fp, &n_expected_fields, &in);
}
if (fp != GMT_stdin) GMT_fclose (fp);
}
point = (struct POINT *) GMT_memory ((void *)point, (size_t)n, sizeof (struct POINT), GMT_program);
grd = (float *) GMT_memory (VNULL, (size_t)(header.nx * header.ny), sizeof (float), GMT_program);
/* Compute weighted averages based on the nearest neighbors */
n_set = n_almost = n_none = 0;
if (!set_empty) empty = GMT_f_NaN;
for (j = ij = 0; j < header.ny; j++) {
for (i = 0; i < header.nx; i++, ij++) {
grd[ij] = empty;
if (!grid_node[ij]) { /* No nearest neighbors */
n_none++;
continue;
}
for (k = 0, go = TRUE; go && k < n_sectors; k++) if (grid_node[ij]->datum[k] < 0) go = FALSE;
if (!go) { /* Not full set of neighbors */
n_almost++;
continue;
}
n_set++;
weight_sum = grd[ij] = 0.0; /* Replace the empty so that we may compute a sum */
for (k = 0; k < n_sectors; k++) {
delta = 3.0 * grid_node[ij]->distance[k] / radius;
weight = 1.0 / (1.0 + delta * delta); /* This is distance weight */
if (weighted) weight *= point[grid_node[ij]->datum[k]].w; /* This is observation weight */
grd[ij] += (float)(weight * point[grid_node[ij]->datum[k]].z);
weight_sum += weight;
}
grd[ij] /= (float)weight_sum;
}
}
if (GMT_write_grd (outfile, &header, grd, 0.0, 0.0, 0.0, 0.0, pad, FALSE)) {
fprintf (stderr, "%s: Error writing file %s\n", GMT_program, outfile);
exit (EXIT_FAILURE);
}
if (gmtdefs.verbose) {
sprintf (line, "%s)\n\0", gmtdefs.d_format);
fprintf (stderr, "%s: %d nodes were assigned an average value\n", GMT_program, n_set);
fprintf (stderr, "%s: %d nodes failed sector criteria and %d nodes had no neighbor points (all set to ", GMT_program, n_almost, n_none);
(GMT_is_dnan (empty)) ? fprintf (stderr, "NaN)\n") : fprintf (stderr, line, empty);
}
GMT_free ((void *)grd);
GMT_free ((void *)point);
GMT_free ((void *)grid_node);
GMT_free ((void *)shrink);
GMT_free ((void *)di);
GMT_free ((void *)x0);
GMT_free ((void *)y0);
GMT_end (argc, argv);
}
struct NODE *add_new_node(int n)
{
struct NODE *new;
new = (struct NODE *) GMT_memory (VNULL, (size_t)1, sizeof (struct NODE), GMT_program);
new->distance = (float *) GMT_memory (VNULL, (size_t)n, sizeof (float), GMT_program);
new->datum = (int *) GMT_memory (VNULL, (size_t)n, sizeof (int), GMT_program);
while (n > 0) new->datum[--n] = -1;
return (new);
}
void assign_node (struct NODE **node, int n_sector, int sector, double distance, int id)
{
/* Allocates node space if not already used and updates the value if closer to node */
if (!(*node)) *node = add_new_node (n_sector);
if ((*node)->datum[sector] == -1 || (*node)->distance[sector] > distance) {
(*node)->distance[sector] = (float)distance;
(*node)->datum[sector] = id;
}
}
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