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Then it reads the hyperslab from this file into a 2-dimensional plane (size 7 x 7) of a 3-dimensional array (size 7 x 7 x 3), as follows (with Dimension 0 offset by 3):
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/************************************************************
This example shows how to write and read a hyperslab. It
is derived from the h5_read.c and h5_write.c examples in
the "Introduction to HDF5".
************************************************************/
#include "hdf5.h"
#define FILE "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
#define X 5 /* dataset dimensions */
#define Y 6
int
main (void)
{
hsize_t dimsf[2]; /* dataset dimensions */
int data[X][Y]; /* data to write */
/*
* Data and output buffer initialization.
*/
hid_t file, dataset; /* handles */
hid_t dataspace;
hid_t memspace;
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 */
hssize_t offset[2]; /* hyperslab offset in the file */
hsize_t count_out[3]; /* size of the hyperslab in memory */
hssize_t offset_out[3]; /* hyperslab offset in memory */
int i, j, k, status_n, rank;
/*********************************************************
This writes data to the HDF5 file.
*********************************************************/
/*
* Data and output buffer initialization.
*/
for (j = 0; j < X; j++) {
for (i = 0; i < Y; i++)
data[j][i] = i + j;
}
/*
* 0 1 2 3 4 5
* 1 2 3 4 5 6
* 2 3 4 5 6 7
* 3 4 5 6 7 8
* 4 5 6 7 8 9
*/
/*
* Create a new file using H5F_ACC_TRUNC access,
* the default file creation properties, and the default file
* access properties.
*/
file = H5Fcreate (FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
/*
* Describe the size of the array and create the data space for fixed
* size dataset.
*/
dimsf[0] = X;
dimsf[1] = Y;
dataspace = H5Screate_simple (RANK, dimsf, NULL);
/*
* Create a new dataset within the file using defined dataspace and
* default dataset creation properties.
*/
dataset = H5Dcreate (file, DATASETNAME, H5T_STD_I32BE, dataspace,
H5P_DEFAULT);
/*
* Write the data to the dataset using default transfer properties.
*/
status = H5Dwrite (dataset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL,
H5P_DEFAULT, data);
/*
* Close/release resources.
*/
H5Sclose (dataspace);
H5Dclose (dataset);
H5Fclose (file);
/*************************************************************
This reads the hyperslab from the sds.h5 file just
created, into a 2-dimensional plane of the 3-dimensional
array.
************************************************************/
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 (FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
dataset = H5Dopen (file, DATASETNAME);
dataspace = H5Dget_space (dataset); /* dataspace handle */
rank = H5Sget_simple_extent_ndims (dataspace);
status_n = H5Sget_simple_extent_dims (dataspace, dims_out, NULL);
printf("\nRank: %d\nDimensions: %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);
printf ("Data:\n ");
for (j = 0; j < NX; j++) {
for (i = 0; i < NY; i++) printf("%d ", data_out[j][i][0]);
printf("\n ");
}
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 and release resources.
*/
H5Dclose (dataset);
H5Sclose (dataspace);
H5Sclose (memspace);
H5Fclose (file);
}
herr_t H5Sselect_hyperslab (hid_t space_id, H5S_seloper_t op,
const hssize_t *start, const hsize_t *stride,
const hsize_t *count, const hsize_t *block )
The start, stride, count, and block arrays must be the same size as the rank of the dataspace.