hdf5/examples/h5_extend.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * 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 how to work with extendible datasets. The dataset 
 *  must be chunked in order to be extendible.
 * 
 *  It is used in the HDF5 Tutorial.
 */


#include "hdf5.h"

#define FILENAME    "extend.h5"
#define DATASETNAME "ExtendibleArray"
#define RANK         2

int
main (void)
{
    hid_t        file;                          /* handles */
    hid_t        dataspace, dataset;  
    hid_t        filespace, memspace;
    hid_t        prop;                     

    hsize_t      dims[2]  = {3, 3};           /* dataset dimensions at creation time */		
    hsize_t      maxdims[2] = {H5S_UNLIMITED, H5S_UNLIMITED};
    herr_t       status;                             
    hsize_t      chunk_dims[2] = {2, 5};
    int          data[3][3] = { {1, 1, 1},    /* data to write */
                                {1, 1, 1},
                                {1, 1, 1} };      

    /* Variables used in extending and writing to the extended portion of dataset */
    hsize_t      size[2];
    hsize_t      offset[2];
    hsize_t      dimsext[2] = {7, 3};         /* extend dimensions */
    int          dataext[7][3] = { {2, 3, 4}, 
                                   {2, 3, 4}, 
                                   {2, 3, 4}, 
                                   {2, 3, 4}, 
                                   {2, 3, 4}, 
                                   {2, 3, 4}, 
                                   {2, 3, 4} };

    /* Variables used in reading data back */
    hsize_t      chunk_dimsr[2];
    hsize_t      dimsr[2];
    hsize_t      i, j;
    int          rdata[10][3];
    herr_t       status_n;                             
    int          rank, rank_chunk;

    /* Create the data space with unlimited dimensions. */
    dataspace = H5Screate_simple (RANK, dims, maxdims); 

    /* Create a new file. If file exists its contents will be overwritten. */
    file = H5Fcreate (FILENAME, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);

    /* Modify dataset creation properties, i.e. enable chunking  */
    prop = H5Pcreate (H5P_DATASET_CREATE);
    status = H5Pset_chunk (prop, RANK, chunk_dims);

    /* Create a new dataset within the file using chunk 
       creation properties.  */
    dataset = H5Dcreate2 (file, DATASETNAME, H5T_NATIVE_INT, dataspace,
                         H5P_DEFAULT, prop, H5P_DEFAULT);

    /* Write data to dataset */
    status = H5Dwrite (dataset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL,
                       H5P_DEFAULT, data);

    /* Extend the dataset. Dataset becomes 10 x 3  */
    size[0] = dims[0]+ dimsext[0];
    size[1] = dims[1];
    status = H5Dset_extent (dataset, size);

    /* Select a hyperslab in extended portion of dataset  */
    filespace = H5Dget_space (dataset);
    offset[0] = 3;
    offset[1] = 0;
    status = H5Sselect_hyperslab (filespace, H5S_SELECT_SET, offset, NULL,
                                  dimsext, NULL);  

    /* Define memory space */
    memspace = H5Screate_simple (RANK, dimsext, NULL); 

    /* Write the data to the extended portion of dataset  */
    status = H5Dwrite (dataset, H5T_NATIVE_INT, memspace, filespace,
                       H5P_DEFAULT, dataext);

    /* Close resources */
    status = H5Dclose (dataset);
    status = H5Pclose (prop);
    status = H5Sclose (dataspace);
    status = H5Sclose (memspace);
    status = H5Sclose (filespace);
    status = H5Fclose (file);

    /********************************************
     * Re-open the file and read the data back. *
     ********************************************/

    file = H5Fopen (FILENAME, H5F_ACC_RDONLY, H5P_DEFAULT);
    dataset = H5Dopen2 (file, DATASETNAME, H5P_DEFAULT);

    filespace = H5Dget_space (dataset);
    rank = H5Sget_simple_extent_ndims (filespace);
    status_n = H5Sget_simple_extent_dims (filespace, dimsr, NULL);

    prop = H5Dget_create_plist (dataset);

    if (H5D_CHUNKED == H5Pget_layout (prop)) 
       rank_chunk = H5Pget_chunk (prop, rank, chunk_dimsr);

    memspace = H5Screate_simple (rank, dimsr, NULL);
    status = H5Dread (dataset, H5T_NATIVE_INT, memspace, filespace,
                      H5P_DEFAULT, rdata);

    printf("\n");
    printf("Dataset: \n");
    for (j = 0; j < dimsr[0]; j++)
    {
       for (i = 0; i < dimsr[1]; i++)
           printf("%d ", rdata[j][i]);
       printf("\n");
    }

    status = H5Pclose (prop);
    status = H5Dclose (dataset);
    status = H5Sclose (filespace);
    status = H5Sclose (memspace);
    status = H5Fclose (file);
}