hdf5/examples/h5_read.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://www.hdfgroup.org/licenses.               *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 *   This example reads hyperslab from the SDS.h5 file
 *   created by h5_write.c program into two-dimensional
 *   plane of the three-dimensional array.
 *   Information about dataset in the SDS.h5 file is obtained.
 */

#include "hdf5.h"

#define H5FILE_NAME "SDS.h5"
#define DATASETNAME "IntArray"
#define NX_SUB      3 /* hyperslab dimensions */
#define NY_SUB      4
#define NX          7 /* output buffer dimensions */
#define NY          7
#define NZ          3
#define RANK        2
#define RANK_OUT    3

int
main(void)
{
    hid_t       file, dataset; /* handles */
    hid_t       datatype, dataspace;
    hid_t       memspace;
    H5T_class_t t_class; /* data type class */
    H5T_order_t order;   /* data order */
    size_t      size;    /*
                          * size of the data element
                          * stored in file
                          */
    hsize_t dimsm[3];    /* memory space dimensions */
    hsize_t dims_out[2]; /* dataset dimensions */
    herr_t  status;

    int data_out[NX][NY][NZ]; /* output buffer */

    hsize_t count[2];      /* size of the hyperslab in the file */
    hsize_t offset[2];     /* hyperslab offset in the file */
    hsize_t count_out[3];  /* size of the hyperslab in memory */
    hsize_t offset_out[3]; /* hyperslab offset in memory */
    int     i, j, k, status_n, rank;

    for (j = 0; j < NX; j++) {
        for (i = 0; i < NY; i++) {
            for (k = 0; k < NZ; k++)
                data_out[j][i][k] = 0;
        }
    }

    /*
     * Open the file and the dataset.
     */
    file    = H5Fopen(H5FILE_NAME, H5F_ACC_RDONLY, H5P_DEFAULT);
    dataset = H5Dopen2(file, DATASETNAME, H5P_DEFAULT);

    /*
     * Get datatype and dataspace handles and then query
     * dataset class, order, size, rank and dimensions.
     */
    datatype = H5Dget_type(dataset); /* datatype handle */
    t_class  = H5Tget_class(datatype);
    if (t_class == H5T_INTEGER)
        printf("Data set has INTEGER type \n");
    order = H5Tget_order(datatype);
    if (order == H5T_ORDER_LE)
        printf("Little endian order \n");

    size = H5Tget_size(datatype);
    printf(" Data size is %d \n", (int)size);

    dataspace = H5Dget_space(dataset); /* dataspace handle */
    rank      = H5Sget_simple_extent_ndims(dataspace);
    status_n  = H5Sget_simple_extent_dims(dataspace, dims_out, NULL);
    printf("rank %d, dimensions %lu x %lu \n", rank, (unsigned long)(dims_out[0]),
           (unsigned long)(dims_out[1]));

    /*
     * Define hyperslab in the dataset.
     */
    offset[0] = 1;
    offset[1] = 2;
    count[0]  = NX_SUB;
    count[1]  = NY_SUB;
    status    = H5Sselect_hyperslab(dataspace, H5S_SELECT_SET, offset, NULL, count, NULL);

    /*
     * Define the memory dataspace.
     */
    dimsm[0] = NX;
    dimsm[1] = NY;
    dimsm[2] = NZ;
    memspace = H5Screate_simple(RANK_OUT, dimsm, NULL);

    /*
     * Define memory hyperslab.
     */
    offset_out[0] = 3;
    offset_out[1] = 0;
    offset_out[2] = 0;
    count_out[0]  = NX_SUB;
    count_out[1]  = NY_SUB;
    count_out[2]  = 1;
    status        = H5Sselect_hyperslab(memspace, H5S_SELECT_SET, offset_out, NULL, count_out, NULL);

    /*
     * Read data from hyperslab in the file into the hyperslab in
     * memory and display.
     */
    status = H5Dread(dataset, H5T_NATIVE_INT, memspace, dataspace, H5P_DEFAULT, data_out);
    for (j = 0; j < NX; j++) {
        for (i = 0; i < NY; i++)
            printf("%d ", data_out[j][i][0]);
        printf("\n");
    }
    /*
     * 0 0 0 0 0 0 0
     * 0 0 0 0 0 0 0
     * 0 0 0 0 0 0 0
     * 3 4 5 6 0 0 0
     * 4 5 6 7 0 0 0
     * 5 6 7 8 0 0 0
     * 0 0 0 0 0 0 0
     */

    /*
     * Close/release resources.
     */
    H5Tclose(datatype);
    H5Dclose(dataset);
    H5Sclose(dataspace);
    H5Sclose(memspace);
    H5Fclose(file);

    return 0;
}