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=== Example === | === Example === | ||
{{ | <syntaxhighlight lang="cpp" line highlight="1,2,7"> | ||
/** | |||
} | Write the simple_xy file, with some of the features of netCDF-4. | ||
This is a very simple example which is based on the simple_xy example, | |||
but whch uses netCDF-4 features, such as compression. | |||
This program writes a 2D netCDF variable (called "data") and fills it | |||
with sample data. It has two dimensions, "x" and "y". | |||
Full documentation for netCDF can be found at: | |||
http://www.unidata.ucar.edu/netcdf/docs | |||
*/ | |||
#include <stdlib.h> | |||
#include <stdio.h> | |||
#include <netcdf.h> | |||
/* Name of the file which will be created */ | |||
#define FILE_NAME "simple_xy_nc4.nc" | |||
/* We write 2D data on a 60 x 120 grid */ | |||
#define NDIMS 2 | |||
#define NX 60 | |||
#define NY 120 | |||
/* Define how to handle errors */ | |||
#define ERRCODE 2 | |||
#define ERR(e) {printf("Error: %s\n", nc_strerror(e)); exit(ERRCODE);} | |||
int | |||
main() | |||
{ | |||
int ncid, x_dimid, y_dimid, varid; | |||
int dimids[NDIMS]; | |||
size_t chunks[NDIMS]; | |||
int shuffle, deflate, deflate_level; | |||
int data_out[NX][NY]; | |||
int x, y, retval; | |||
/* Set the data layout */ | |||
shuffle = NC_SHUFFLE; | |||
deflate = 1; | |||
deflate_level = 1; | |||
/* Create some nonsense data for testing purposes */ | |||
for (x = 0; x < NX; x++) | |||
for (y = 0; y < NY; y++) | |||
data_out[x][y] = x * NY + y; | |||
/* Create the file. The NC_NETCDF4 parameter indicates that the file type is NetCDF-4/HDF5 */ | |||
if ((retval = nc_create(FILE_NAME, NC_NETCDF4, &ncid))) | |||
ERR(retval); | |||
/* Define the dimensions */ | |||
if ((retval = nc_def_dim(ncid, "x", NX, &x_dimid))) | |||
ERR(retval); | |||
if ((retval = nc_def_dim(ncid, "y", NY, &y_dimid))) | |||
ERR(retval); | |||
/* Create the variables */ | |||
dimids[0] = x_dimid; | |||
dimids[1] = y_dimid; | |||
chunks[0] = NX/4; | |||
chunks[1] = NY/4; | |||
/* Define the variables */ | |||
if ((retval = nc_def_var(ncid, "data", NC_INT, NDIMS, | |||
dimids, &varid))) | |||
ERR(retval); | |||
if ((retval = nc_def_var_chunking(ncid, varid, 0, &chunks[0]))) | |||
ERR(retval); | |||
if ((retval = nc_def_var_deflate(ncid, varid, shuffle, deflate, | |||
deflate_level))) | |||
ERR(retval); | |||
/* Write the data to the file */ | |||
if ((retval = nc_put_var_int(ncid, varid, &data_out[0][0]))) | |||
ERR(retval); | |||
/* Close the file */ | |||
if ((retval = nc_close(ncid))) | |||
ERR(retval); | |||
printf("*** SUCCESS in writing the file simple_xy_nc4.nc!\n"); | |||
return 0; | |||
} | |||
</syntaxhighlight> | |||