h5ex_d_unlimadd.c

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

  This example shows how to create and extend an unlimited
  dataset.  The program first writes integers to a dataset
  with dataspace dimensions of DIM0xDIM1, then closes the
  file.  Next, it reopens the file, reads back the data,
  outputs it to the screen, extends the dataset, and writes
  new data to the extended portions of the dataset.  Finally
  it reopens the file again, reads back the data, and
  outputs it to the screen.

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

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

#define FILE    "h5ex_d_unlimadd.h5"
#define DATASET "DS1"
#define DIM0    4
#define DIM1    7
#define EDIM0   6
#define EDIM1   10
#define CHUNK0  4
#define CHUNK1  4

int
main(void)
{
    hid_t   file  = H5I_INVALID_HID;
    hid_t   space = H5I_INVALID_HID;
    hid_t   dset  = H5I_INVALID_HID;
    hid_t   dcpl  = H5I_INVALID_HID;
    herr_t  status;
    hsize_t dims[2]    = {DIM0, DIM1};
    hsize_t extdims[2] = {EDIM0, EDIM1};
    hsize_t maxdims[2];
    hsize_t chunk[2] = {CHUNK0, CHUNK1};
    hsize_t start[2];
    hsize_t count[2];
    int     wdata[DIM0][DIM1];    /* Write buffer */
    int     wdata2[EDIM0][EDIM1]; /* Write buffer for extension */
    int   **rdata = NULL;         /* Read buffer */
    int     ndims;
    hsize_t i, j;

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

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

    /*
     * Create dataspace with unlimited dimensions.
     */
    maxdims[0] = H5S_UNLIMITED;
    maxdims[1] = H5S_UNLIMITED;
    space      = H5Screate_simple(2, dims, maxdims);

    /*
     * Create the dataset creation property list, and set the chunk
     * size.
     */
    dcpl   = H5Pcreate(H5P_DATASET_CREATE);
    status = H5Pset_chunk(dcpl, 2, chunk);

    /*
     * Create the unlimited dataset.
     */
    dset = H5Dcreate(file, DATASET, H5T_STD_I32LE, space, H5P_DEFAULT, dcpl, H5P_DEFAULT);

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

    /*
     * Close and release resources.
     */
    status = H5Pclose(dcpl);
    status = H5Dclose(dset);
    status = H5Sclose(space);
    status = H5Fclose(file);

    /*
     * In this next section we read back the data, extend the dataset,
     * and write new data to the extended portions.
     */

    /*
     * Open file and dataset using the default properties.
     */
    file = H5Fopen(FILE, H5F_ACC_RDWR, H5P_DEFAULT);
    dset = H5Dopen(file, DATASET, H5P_DEFAULT);

    /*
     * Get dataspace and allocate memory for read buffer.  This is a
     * two dimensional dataset so the dynamic allocation must be done
     * in steps.
     */
    space = H5Dget_space(dset);
    ndims = H5Sget_simple_extent_dims(space, dims, NULL);

    /*
     * Allocate array of pointers to rows.
     */
    rdata = (int **)malloc(dims[0] * sizeof(int *));

    /*
     * Allocate space for integer data.
     */
    rdata[0] = (int *)malloc(dims[0] * dims[1] * sizeof(int));

    /*
     * Set the rest of the pointers to rows to the correct addresses.
     */
    for (i = 1; i < dims[0]; i++)
        rdata[i] = rdata[0] + i * dims[1];

    /*
     * 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("Dataset before extension:\n");
    for (i = 0; i < dims[0]; i++) {
        printf(" [");
        for (j = 0; j < dims[1]; j++)
            printf(" %3d", rdata[i][j]);
        printf("]\n");
    }

    status = H5Sclose(space);

    /*
     * Extend the dataset.
     */
    status = H5Dset_extent(dset, extdims);

    /*
     * Retrieve the dataspace for the newly extended dataset.
     */
    space = H5Dget_space(dset);

    /*
     * Initialize data for writing to the extended dataset.
     */
    for (i = 0; i < EDIM0; i++)
        for (j = 0; j < EDIM1; j++)
            wdata2[i][j] = j;

    /*
     * Select the entire dataspace.
     */
    status = H5Sselect_all(space);

    /*
     * Subtract a hyperslab reflecting the original dimensions from the
     * selection.  The selection now contains only the newly extended
     * portions of the dataset.
     */
    start[0] = 0;
    start[1] = 0;
    count[0] = dims[0];
    count[1] = dims[1];
    status   = H5Sselect_hyperslab(space, H5S_SELECT_NOTB, start, NULL, count, NULL);

    /*
     * Write the data to the selected portion of the dataset.
     */
    status = H5Dwrite(dset, H5T_NATIVE_INT, H5S_ALL, space, H5P_DEFAULT, wdata2[0]);

    /*
     * Close and release resources.
     */
    free(rdata[0]);
    free(rdata);
    status = H5Dclose(dset);
    status = H5Sclose(space);
    status = H5Fclose(file);

    /*
     * Now we simply read back the data and output it to the screen.
     */

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

    /*
     * Get dataspace and allocate memory for the read buffer as before.
     */
    space    = H5Dget_space(dset);
    ndims    = H5Sget_simple_extent_dims(space, dims, NULL);
    rdata    = (int **)malloc(dims[0] * sizeof(int *));
    rdata[0] = (int *)malloc(dims[0] * dims[1] * sizeof(int));
    for (i = 1; i < dims[0]; i++)
        rdata[i] = rdata[0] + i * dims[1];

    /*
     * 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("\nDataset after extension:\n");
    for (i = 0; i < dims[0]; i++) {
        printf(" [");
        for (j = 0; j < dims[1]; j++)
            printf(" %3d", rdata[i][j]);
        printf("]\n");
    }

    /*
     * Close and release resources.
     */
    free(rdata[0]);
    free(rdata);
    status = H5Dclose(dset);
    status = H5Sclose(space);
    status = H5Fclose(file);

    return 0;
}