hdf5/doc/html/Tutor/examples/h5_read.c

/*  
 *   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 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

int
main (void)
{
    hid_t       file, dataset;         /* handles */
    hid_t       datatype, dataspace;   
    hid_t       memspace; 
    H5T_class_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(FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
    dataset = H5Dopen(file, DATASETNAME);

    /*
     * Get datatype and dataspace handles and then query
     * dataset class, order, size, rank and dimensions.
     */
    datatype  = H5Dget_type(dataset);     /* datatype handle */ 
    class     = H5Tget_class(datatype);
    if (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", 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;
}