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=== Example ===
=== Example ===
Here is a simple example demonstrating the compression with NetCDF. This program writes a 2D netCDF variable (called "data") and fills it
There is a relatively simple example demonstrating the use of the NetCDF which can be found at the following [https://www.unidata.ucar.edu/software/netcdf/netcdf-4/newdocs/netcdf-tutorial/simple_005fxy_005fwr_002ec.html#simple_005fxy_005fwr_002ec link]. In that example the code writes a 2D netCDF variable (called "data") and fills it
with sample data.  It has two dimensions, "x" and "y".
with sample data.  It has two dimensions, "x" and "y".
   
   
Full documentation for netCDF can be found at:
In order to compile that code you need to have the NetCDF4 library set in your environment (in your LD_LIBRARY_PATH to be precisely) :
http://www.unidata.ucar.edu/netcdf/docs
 
<syntaxhighlight lang="cpp" line highlight="">
#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>
You can compile this example in the following manner if you have the NetCDF4 and HDF5 libraries in your environment:
{{Command
{{Command
|gcc ex_netcdf4.c -lnetcdf
|gcc ex_netcdf4.c -lnetcdf
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