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HOME > Monitoring_and_Data > Oceanic and Atmospheric Data > Reanalysis: Atmospheric Data >
wgrib2
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wgrib2: a sample function
Introduction
Wgrib2 is "function" driven. Every option on the command line now calls a function.
Each function is called several times, for initialization (mode=-1), for each grib
record (mode=0,1,2 depending on the verbosity index) and for clean up (mode=-2).
Here is a sample function.
#include <stdio.h>
#include "grb2.h"
#include "wgrib2.h"
#include "fnlist.h"
extern int decode;
extern int need_output_file;
/*
* HEADER:100:min:inv:0:print minimum value
* the above line is needed by each command line option
* HEADER:sort-order:type-of-function:number-of-arguments:description
*/
int f_min(int mode, unsigned char **sec, float *data, int ndata, FILE *out) {
double mn;
int ok, i;
if (mode == -1) decode = 1;
else {
mn = ok = 0;
for (i = 0; i < ndata; i++) {
if (!UNDEFINED_VAL(data[i])) {
if (ok) mn = mn < data[i] ? mn : data[i];
else { ok = 1; mn = data[i]; }
}
}
if (ok) printf("min=%lg",mn);
else printf("min=undefined");
}
return 0;
}
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