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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the COPYING file, which can be found at the root of the source code *
* distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases. *
* If you do not have access to either file, you may request a copy from *
* help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* This example illustrates how to create a compressed dataset.
* It is used in the HDF5 Tutorial.
*/
#include "hdf5.h"
#define FILE "cmprss.h5"
#define RANK 2
#define DIM0 100
#define DIM1 20
int main () {
hid_t file_id, dataset_id, dataspace_id; /* identifiers */
hid_t plist_id;
size_t nelmts;
unsigned flags, filter_info;
H5Z_filter_t filter_type;
herr_t status;
hsize_t dims[2];
hsize_t cdims[2];
int i,j, numfilt;
int buf[DIM0][DIM1];
int rbuf [DIM0][DIM1];
/* Uncomment these variables to use SZIP compression
unsigned szip_options_mask;
unsigned szip_pixels_per_block;
*/
/* Create a file. */
file_id = H5Fcreate (FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
/* Create dataset "Compressed Data" in the group using absolute name. */
dims[0] = DIM0;
dims[1] = DIM1;
dataspace_id = H5Screate_simple (RANK, dims, NULL);
plist_id = H5Pcreate (H5P_DATASET_CREATE);
/* Dataset must be chunked for compression */
cdims[0] = 20;
cdims[1] = 20;
status = H5Pset_chunk (plist_id, 2, cdims);
/* Set ZLIB / DEFLATE Compression using compression level 6.
* To use SZIP Compression comment out these lines.
*/
status = H5Pset_deflate (plist_id, 6);
/* Uncomment these lines to set SZIP Compression
szip_options_mask = H5_SZIP_NN_OPTION_MASK;
szip_pixels_per_block = 16;
status = H5Pset_szip (plist_id, szip_options_mask, szip_pixels_per_block);
*/
dataset_id = H5Dcreate2 (file_id, "Compressed_Data", H5T_STD_I32BE,
dataspace_id, H5P_DEFAULT, plist_id, H5P_DEFAULT);
for (i = 0; i< DIM0; i++)
for (j=0; j<DIM1; j++)
buf[i][j] = i+j;
status = H5Dwrite (dataset_id, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, buf);
status = H5Sclose (dataspace_id);
status = H5Dclose (dataset_id);
status = H5Pclose (plist_id);
status = H5Fclose (file_id);
/* Now reopen the file and dataset in the file. */
file_id = H5Fopen (FILE, H5F_ACC_RDWR, H5P_DEFAULT);
dataset_id = H5Dopen2 (file_id, "Compressed_Data", H5P_DEFAULT);
/* Retrieve filter information. */
plist_id = H5Dget_create_plist (dataset_id);
numfilt = H5Pget_nfilters (plist_id);
printf ("Number of filters associated with dataset: %i\n", numfilt);
for (i=0; i<numfilt; i++) {
nelmts = 0;
filter_type = H5Pget_filter2 (plist_id, 0, &flags, &nelmts, NULL, 0, NULL,
&filter_info);
printf ("Filter Type: ");
switch (filter_type) {
case H5Z_FILTER_DEFLATE:
printf ("H5Z_FILTER_DEFLATE\n");
break;
case H5Z_FILTER_SZIP:
printf ("H5Z_FILTER_SZIP\n");
break;
default:
printf ("Other filter type included.\n");
}
}
status = H5Dread (dataset_id, H5T_NATIVE_INT, H5S_ALL, H5S_ALL,
H5P_DEFAULT, rbuf);
status = H5Dclose (dataset_id);
status = H5Pclose (plist_id);
status = H5Fclose (file_id);
}
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