/****************************************************************************/
/* This program demonstrates how to read a field from a GMAO HDF-EOS */
/* product using the HDF-EOS library. It will take a file name and */
/* field name on the command line, read the first time of the given */
/* field, calculate an average of that time and print the average. */
/* */
/* usage: avg <file name> <field name> */
/* */
/* Rob Lucchesi */
/* rlucchesi@GMAO.gsfc.nasa.gov */
/* 2/12/1999 */
/****************************************************************************/
#include "hdf.h"
#include "mfhdf.h"
#include <stdio.h>
#define XDIM 288
#define YDIM 181
#define ZDIM 36
main(int argc,char *argv[]) {
int32 sd_id, sds_id, status;
int32 sds_index;
int32 start[4], edges[4], stride[4];
char *fname, *vname;
float32 data_array[ZDIM][YDIM][XDIM];
float32 avg, sum;
int32 i,j,k;
int32 file_id, gd_id;
if (argc != 3) {
printf("Usage: avg <filename> <field> \n");
exit (-1);
}
fname = argv[1];
vname = argv[2];
/* Open the file (read-only) */
file_id = GDopen (fname, DFACC_RDONLY);
if (file_id < 0) {
printf ("Could not open %s\n",fname);
exit(-1);
}
/* Attach to the EOS grid contained within the file. */
/* The GMAO uses the generic name "EOSGRID" for the grid in all products. */
gd_id = GDattach (file_id,"EOSGRID");
if (gd_id < 0) {
printf ("Could not open %s\n",fname);
exit(-1);
}
/* Set positioning arrays to read the entire field at the first time. */
start[0] = 0;
start[1] = 0;
start[2] = 0;
start[3] = 0;
stride[0] = 1;
stride[1] = 1;
stride[2] = 1;
stride[3] = 1;
edges[0] = 1;
edges[1] = ZDIM;
edges[2] = YDIM;
edges[3] = XDIM;
/*
In this program, we read the entire field. By manipulating the start
and edges arrays, it is possible to read a subset of the entire array.
For example, to read a 3D section defined by x=100,224; y=50,149;
z=15,16 you would set the start and edges arrays to the following:
start[0] = 0; time start location
start[1] = 15; z-dim start location
start[2] = 50; y-dim start location
start[3] = 100; x-dim start location
edges[0] = 1; time length
edges[1] = 2; z-dim length
edges[2] = 100; y-dim length
edges[3] = 125; x-dim length
*/
/* Read the data into data_array */
status = GDreadfield (gd_id, vname, start, stride, edges, data_array);
printf ("Read status=%d\n",status);
/* Calculate and print the average */
sum=0.0;
for (i=0; i<XDIM; i++)
for (j=0; j<YDIM; j++)
for (k=0; k<ZDIM; k++)
sum += data_array[k][j][i];
avg = sum/(XDIM*YDIM*ZDIM);
printf ("Average of %s in 3 dimensions is=%f\n",vname,avg);
/* Close file. */
status = GDdetach (gd_id);
status = GDclose (file_id);
}
/****************************************************************************/
/* This program demonstrates how to read a field from a GMAO HDF-EOS */
/* product using the HDF library (HDF-EOS not required). It will take */
/* a file name and field name on the command line, read the first time */
/* of the given field, calculate an average of that time and print the average. */
/* */
/* usage: avg <file name> <field name> */
/* */
/* Rob Lucchesi */
/* rlucchesi@gmao.gsfc.nasa.gov */
/* 2/12/1999 */
/****************************************************************************/
#include "hdf.h"
#include "mfhdf.h"
#include <stdio.h>
#define XDIM 288
#define YDIM 181
#define ZDIM 36
main(int argc,char *argv[]) {
int32 sd_id, sds_id, status;
int32 sds_index;
int32 start[4], edges[4], stride[4];
char *fname, *vname;
float32 data_array[ZDIM][YDIM][XDIM];
float32 avg, sum;
int32 i,j,k;
if (argc != 3) {
printf("Usage: avg <filename> <field> \n");
exit (-1);
}
fname = argv[1];
vname = argv[2];
/* Open the file (read-only) */
sd_id = SDstart (fname, DFACC_RDONLY);
if (sd_id < 0) {
printf ("Could not open %s\n",fname);
exit(-1);
}
/* Find the index and ID of the SDS for the given variable name. */
sds_index = SDnametoindex (sd_id, vname);
if (sds_index < 0) {
printf ("Could not find %s\n",vname);
exit(-1);
}
sds_id = SDselect (sd_id,sds_index);
/* Set positioning arrays to read the entire field at the first time. */
start[0] = 0;
start[1] = 0;
start[2] = 0;
start[3] = 0;
stride[0] = 1;
stride[1] = 1;
stride[2] = 1;
stride[3] = 1;
edges[0] = 1;
edges[1] = ZDIM;
edges[2] = YDIM;
edges[3] = XDIM;
/*
In this program, we read the entire field. By manipulating the start
and edges arrays, it is possible to read a subset of the entire array.
For example, to read a 3D section defined by x=100,224; y=50,149;
z=15,16 you would set the start and edges arrays to the following:
start[0] = 0; time start location
start[1] = 15; z-dim start location
start[2] = 50; y-dim start location
start[3] = 100; x-dim start location
edges[0] = 1; time length
edges[1] = 2; z-dim length
edges[2] = 100; y-dim length
edges[3] = 125; x-dim length
*/
/* Read the data into data_array */
status = SDreaddata (sds_id, start, stride, edges, (VOIDP) data_array);
printf ("read status=%d\n",status);
/* Calculate and print the average */
sum=0.0;
for (i=0; i<XDIM; i++)
for (j=0; j<YDIM; j++)
for (k=0; k<ZDIM; k++)
sum += data_array[k][j][i];
avg = sum/(XDIM*YDIM*ZDIM);
printf ("Average of %s in 3 dimensions is=%f\n",vname,avg);
/* Close file. */
status = SDendaccess (sds_id);
status = SDend (sd_id);
}