hdf5/examples/h5_extend_write.c

/*  
 *   This example shows how to work with extendible dataset.
 *   In the current version of the library dataset MUST be
 *   chunked.
 *   
 */
 
#include "hdf5.h"

#define H5FILE_NAME        "SDSextendible.h5"
#define DATASETNAME "ExtendibleArray" 
#define RANK         2
#define NX     10
#define NY     5 

int
main (void)
{
    hid_t       file;                          /* handles */
    hid_t       dataspace, dataset;  
    hid_t       filespace;                   
    hid_t       cparms;                     
    hsize_t      dims[2]  = { 3, 3};            /*
						 * dataset dimensions				
						 * at the creation time
						 */
    hsize_t      dims1[2] = { 3, 3};            /* data1 dimensions */ 
    hsize_t      dims2[2] = { 7, 1};            /* data2 dimensions */  
    hsize_t      dims3[2] = { 2, 2};            /* data3 dimensions */ 

    hsize_t      maxdims[2] = {H5S_UNLIMITED, H5S_UNLIMITED};
    hsize_t      chunk_dims[2] ={2, 5};
    hsize_t      size[2];
    hssize_t     offset[2];

    herr_t      status;                             

    int         data1[3][3] = { {1, 1, 1},       /* data to write */
				{1, 1, 1},
				{1, 1, 1} };      

    int         data2[7]    = { 2, 2, 2, 2, 2, 2, 2};

    int         data3[2][2] = { {3, 3},
				{3, 3} };

    /*
     * Create the data space with unlimited dimensions. 
     */
    dataspace = H5Screate_simple(RANK, dims, maxdims); 

    /*
     * Create a new file. If file exists its contents will be overwritten.
     */
    file = H5Fcreate(H5FILE_NAME, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);

    /* 
     * Modify dataset creation properties, i.e. enable chunking.
     */
    cparms = H5Pcreate (H5P_DATASET_CREATE);
    status = H5Pset_chunk( cparms, RANK, chunk_dims);

    /*
     * Create a new dataset within the file using cparms
     * creation properties.
     */
    dataset = H5Dcreate(file, DATASETNAME, H5T_NATIVE_INT, dataspace,
			cparms);

    /*
     * Extend the dataset. This call assures that dataset is at least 3 x 3.
     */
    size[0]   = 3; 
    size[1]   = 3; 
    status = H5Dextend (dataset, size);

    /*
     * Select a hyperslab.
     */
    filespace = H5Dget_space (dataset);
    offset[0] = 0;
    offset[1] = 0;
    status = H5Sselect_hyperslab(filespace, H5S_SELECT_SET, offset, NULL,
				 dims1, NULL);  

    /*
     * Write the data to the hyperslab.
     */
    status = H5Dwrite(dataset, H5T_NATIVE_INT, dataspace, filespace,
		      H5P_DEFAULT, data1);

    /*
     * Extend the dataset. Dataset becomes 10 x 3.
     */
    dims[0]   = dims1[0] + dims2[0];
    size[0]   = dims[0];  
    size[1]   = dims[1]; 
    status = H5Dextend (dataset, size);

    /*
     * Select a hyperslab.
     */
    filespace = H5Dget_space (dataset);
    offset[0] = 3;
    offset[1] = 0;
    status = H5Sselect_hyperslab(filespace, H5S_SELECT_SET, offset, NULL,
				 dims2, NULL);  

    /*
     * Define memory space
     */
    dataspace = H5Screate_simple(RANK, dims2, NULL); 

    /*
     * Write the data to the hyperslab.
     */
    status = H5Dwrite(dataset, H5T_NATIVE_INT, dataspace, filespace,
		      H5P_DEFAULT, data2);

    /*
     * Extend the dataset. Dataset becomes 10 x 5.
     */
    dims[1]   = dims1[1] + dims3[1];
    size[0]   = dims[0];  
    size[1]   = dims[1]; 
    status = H5Dextend (dataset, size);

    /*
     * Select a hyperslab
     */
    filespace = H5Dget_space (dataset);
    offset[0] = 0;
    offset[1] = 3;
    status = H5Sselect_hyperslab(filespace, H5S_SELECT_SET, offset, NULL, 
				 dims3, NULL);  

    /*
     * Define memory space.
     */
    dataspace = H5Screate_simple(RANK, dims3, NULL); 

    /*
     * Write the data to the hyperslab.
     */
    status = H5Dwrite(dataset, H5T_NATIVE_INT, dataspace, filespace,
		      H5P_DEFAULT, data3);

    /*
     * Resulting dataset
     * 
     *	 3 3 3 2 2
     *	 3 3 3 2 2
     *	 3 3 3 0 0
     *	 2 0 0 0 0
     *	 2 0 0 0 0
     *	 2 0 0 0 0
     *	 2 0 0 0 0
     *	 2 0 0 0 0
     *	 2 0 0 0 0
     *	 2 0 0 0 0
     */
    /*
     * Close/release resources.
     */
    H5Dclose(dataset);
    H5Sclose(dataspace);
    H5Sclose(filespace);
    H5Fclose(file);

    return 0;
}