hdf5/HDF5Examples/C/H5D/h5ex_d_hyper.c

/************************************************************

  This example shows how to read and write data to a
  dataset by hyberslabs.  The program first writes integers
  in a hyperslab selection to a dataset with dataspace
  dimensions of DIM0xDIM1, then closes the file.  Next, it
  reopens the file, reads back the data, and outputs it to
  the screen.  Finally it reads the data again using a
  different hyperslab selection, and outputs the result to
  the screen.

 ************************************************************/

#include "hdf5.h"
#include <stdio.h>
#include <stdlib.h>

#define FILE    "h5ex_d_hyper.h5"
#define DATASET "DS1"
#define DIM0    6
#define DIM1    8

int
main(void)
{
    hid_t   file  = H5I_INVALID_HID;
    hid_t   space = H5I_INVALID_HID;
    hid_t   dset  = H5I_INVALID_HID;
    herr_t  status;
    hsize_t dims[2] = {DIM0, DIM1};
    hsize_t start[2];
    hsize_t stride[2];
    hsize_t count[2];
    hsize_t block[2];
    int     wdata[DIM0][DIM1]; /* Write buffer */
    int     rdata[DIM0][DIM1]; /* Read buffer */
    hsize_t i, j;

    /*
     * Initialize data to "1", to make it easier to see the selections.
     */
    for (i = 0; i < DIM0; i++)
        for (j = 0; j < DIM1; j++)
            wdata[i][j] = 1;

    /*
     * Print the data to the screen.
     */
    printf("Original Data:\n");
    for (i = 0; i < DIM0; i++) {
        printf(" [");
        for (j = 0; j < DIM1; j++)
            printf(" %3d", wdata[i][j]);
        printf("]\n");
    }

    /*
     * Create a new file using the default properties.
     */
    file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);

    /*
     * Create dataspace.  Setting maximum size to NULL sets the maximum
     * size to be the current size.
     */
    space = H5Screate_simple(2, dims, NULL);

    /*
     * Create the dataset.  We will use all default properties for this
     * example.
     */
    dset = H5Dcreate(file, DATASET, H5T_STD_I32LE, space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);

    /*
     * Define and select the first part of the hyperslab selection.
     */
    start[0]  = 0;
    start[1]  = 0;
    stride[0] = 3;
    stride[1] = 3;
    count[0]  = 2;
    count[1]  = 3;
    block[0]  = 2;
    block[1]  = 2;
    status    = H5Sselect_hyperslab(space, H5S_SELECT_SET, start, stride, count, block);

    /*
     * Define and select the second part of the hyperslab selection,
     * which is subtracted from the first selection by the use of
     * H5S_SELECT_NOTB
     */
    block[0] = 1;
    block[1] = 1;
    status   = H5Sselect_hyperslab(space, H5S_SELECT_NOTB, start, stride, count, block);

    /*
     * Write the data to the dataset.
     */
    status = H5Dwrite(dset, H5T_NATIVE_INT, H5S_ALL, space, H5P_DEFAULT, wdata[0]);

    /*
     * Close and release resources.
     */
    status = H5Dclose(dset);
    status = H5Sclose(space);
    status = H5Fclose(file);

    /*
     * Now we begin the read section of this example.
     */

    /*
     * Open file and dataset using the default properties.
     */
    file = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
    dset = H5Dopen(file, DATASET, H5P_DEFAULT);

    /*
     * Read the data using the default properties.
     */
    status = H5Dread(dset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, rdata[0]);

    /*
     * Output the data to the screen.
     */
    printf("\nData as written to disk by hyberslabs:\n");
    for (i = 0; i < DIM0; i++) {
        printf(" [");
        for (j = 0; j < DIM1; j++)
            printf(" %3d", rdata[i][j]);
        printf("]\n");
    }

    /*
     * Initialize the read array.
     */
    for (i = 0; i < DIM0; i++)
        for (j = 0; j < DIM1; j++)
            rdata[i][j] = 0;

    /*
     * Define and select the hyperslab to use for reading.
     */
    space     = H5Dget_space(dset);
    start[0]  = 0;
    start[1]  = 1;
    stride[0] = 4;
    stride[1] = 4;
    count[0]  = 2;
    count[1]  = 2;
    block[0]  = 2;
    block[1]  = 3;
    status    = H5Sselect_hyperslab(space, H5S_SELECT_SET, start, stride, count, block);

    /*
     * Read the data using the previously defined hyperslab.
     */
    status = H5Dread(dset, H5T_NATIVE_INT, H5S_ALL, space, H5P_DEFAULT, rdata[0]);

    /*
     * Output the data to the screen.
     */
    printf("\nData as read from disk by hyperslab:\n");
    for (i = 0; i < DIM0; i++) {
        printf(" [");
        for (j = 0; j < DIM1; j++)
            printf(" %3d", rdata[i][j]);
        printf("]\n");
    }

    /*
     * Close and release resources.
     */
    status = H5Dclose(dset);
    status = H5Sclose(space);
    status = H5Fclose(file);

    return 0;
}