h5ex_d_transform.c

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

  This example shows how to read and write data to a dataset
  using a data transform expression.  The program first
  writes integers to a dataset using the transform
  expression TRANSFORM, then closes the file.  Next, it
  reopens the file, reads back the data without a transform,
  and outputs the data to the screen.  Finally it reads the
  data using the transform expression RTRANSFORM and outputs
  the results to the screen.

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

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

#define FILENAME   "h5ex_d_transform.h5"
#define DATASET    "DS1"
#define DIM0       4
#define DIM1       7
#define TRANSFORM  "x+1"
#define RTRANSFORM "x-1"

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

    /*
     * Initialize data.
     */
    for (i = 0; i < DIM0; i++)
        for (j = 0; j < DIM1; j++)
            wdata[i][j] = i * j - j;

    /*
     * Output 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(FILENAME, 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 transfer property list and define the
     * transform expression.
     */
    dxpl   = H5Pcreate(H5P_DATASET_XFER);
    status = H5Pset_data_transform(dxpl, TRANSFORM);

    /*
     * Create the dataset using the default properties.  Unfortunately
     * we must save as a native type or the transform operation will
     * fail.
     */
    dset = H5Dcreate(file, DATASET, H5T_NATIVE_INT, space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);

    /*
     * Write the data to the dataset using the dataset transfer
     * property list.
     */
    status = H5Dwrite(dset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, dxpl, wdata[0]);

    /*
     * Close and release resources.
     */
    status = H5Pclose(dxpl);
    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(FILENAME, 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 with transform \"%s\":\n", TRANSFORM);
    for (i = 0; i < DIM0; i++) {
        printf(" [");
        for (j = 0; j < DIM1; j++)
            printf(" %3d", rdata[i][j]);
        printf("]\n");
    }

    /*
     * Create the dataset transfer property list and define the
     * transform expression.
     */
    dxpl   = H5Pcreate(H5P_DATASET_XFER);
    status = H5Pset_data_transform(dxpl, RTRANSFORM);

    /*
     * Read the data using the dataset transfer property list.
     */
    status = H5Dread(dset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, dxpl, rdata[0]);

    /*
     * Output the data to the screen.
     */
    printf("\nData as written with transform \"%s\" and read with transform \"%s\":\n", TRANSFORM,
           RTRANSFORM);
    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 = H5Pclose(dxpl);
    status = H5Dclose(dset);
    status = H5Fclose(file);

    return 0;
}