read_latlon.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#include <limits.h>
#include "grb2.h"
#include "wgrib2.h"
#include "fnlist.h"


/* Public Domain 7/2019    Wesley Ebisuzaki
 *
 * latlon_list.c
 *
 * read latlon from string
 *
 */

unsigned int read_latlon(const char *arg, double **lon, double **lat) {
    unsigned int n_out, i;
    int j, k;
    double *llat, *llon;
        n_out = 0;
        for (i = 0; i < strlen(arg); i++) {
            if (arg[i] == ':') n_out++;
        }
	if (n_out % 2 == 0) return 0;
        n_out = (n_out+1)/2;
        
        *lat = llat = (double *) malloc(sizeof(double) * (size_t) n_out);
        *lon = llon = (double *) malloc(sizeof(double) * (size_t) n_out);

        k = sscanf(arg, "%lf:%lf%n", llon, llat, &j);
        if (k != 2) fatal_error("get_latlon_list, no grid point locations","");
        for (i=1; i < n_out; i++) {
            arg += j;
            k = sscanf(arg, ":%lf:%lf%n", llon+i, llat+i, &j);
            if (k != 2) fatal_error("get_latlon_list: missing grid point locations: %s",arg);
        }
	/* check values */
        for (i=0; i < n_out; i++) {
	    if (llat[i] > 90.0 || llat[i] < -90.0) return (unsigned int) 0;
	    if (llon[i] < 0.0) llon[i] += 360.0;
	    if (llon[i] < 0.0 || llon[i] > 360.0) return (unsigned int) 0;
        }
        return n_out;
}