321 lines
8 KiB
Java
321 lines
8 KiB
Java
/************************************************************
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This example shows how to read and write data to a dataset
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using gzip compression (also called zlib or deflate). The
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program first checks if gzip compression is available,
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then if it is it writes integers to a dataset using gzip,
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then closes the file. Next, it reopens the file, reads
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back the data, and outputs the type of compression and the
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maximum value in the dataset to the screen.
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This file is intended for use with HDF5 Library verion 1.6
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************************************************************/
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package datasets;
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import java.util.EnumSet;
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import java.util.HashMap;
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import java.util.Map;
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import ncsa.hdf.hdf5lib.H5;
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import ncsa.hdf.hdf5lib.HDF5Constants;
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public class H5Ex_D_Gzip {
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private static String FILENAME = "h5ex_d_gzip.h5";
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private static String DATASETNAME = "DS1";
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private static final int DIM_X = 32;
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private static final int DIM_Y = 64;
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private static final int CHUNK_X = 4;
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private static final int CHUNK_Y = 8;
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private static final int RANK = 2;
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private static final int NDIMS = 2;
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// Values for the status of space allocation
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enum H5Z_filter {
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H5Z_FILTER_ERROR(-1), H5Z_FILTER_NONE(0), H5Z_FILTER_DEFLATE(1), H5Z_FILTER_SHUFFLE(
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2), H5Z_FILTER_FLETCHER32(3), H5Z_FILTER_SZIP(4), H5Z_FILTER_NBIT(5), H5Z_FILTER_SCALEOFFSET(
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6), H5Z_FILTER_RESERVED(256), H5Z_FILTER_MAX(65535);
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private static final Map<Integer, H5Z_filter> lookup = new HashMap<Integer, H5Z_filter>();
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static {
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for (H5Z_filter s : EnumSet.allOf(H5Z_filter.class))
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lookup.put(s.getCode(), s);
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}
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private int code;
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H5Z_filter(int layout_type) {
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this.code = layout_type;
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}
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public int getCode() {
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return this.code;
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}
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public static H5Z_filter get(int code) {
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return lookup.get(code);
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}
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}
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private static boolean checkGzipFilter() {
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try {
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int available = H5.H5Zfilter_avail(H5Z_filter.H5Z_FILTER_DEFLATE
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.getCode());
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if (available == 0) {
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System.out.println("gzip filter not available.");
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return false;
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}
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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try {
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int filter_info = H5.H5Zget_filter_info(HDF5Constants.H5Z_FILTER_DEFLATE);
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if (((filter_info & HDF5Constants.H5Z_FILTER_CONFIG_ENCODE_ENABLED) == 0)
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|| ((filter_info & HDF5Constants.H5Z_FILTER_CONFIG_DECODE_ENABLED) == 0)) {
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System.out
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.println("gzip filter not available for encoding and decoding.");
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return false;
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}
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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return true;
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}
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private static void writeGzip() {
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int file_id = -1;
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int filespace_id = -1;
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int dataset_id = -1;
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int dcpl_id = -1;
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long[] dims = { DIM_X, DIM_Y };
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long[] chunk_dims = { CHUNK_X, CHUNK_Y };
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int[][] dset_data = new int[DIM_X][DIM_Y];
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// Initialize data.
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for (int indx = 0; indx < DIM_X; indx++)
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for (int jndx = 0; jndx < DIM_Y; jndx++)
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dset_data[indx][jndx] = indx * jndx - jndx;
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// Create a new file using default properties.
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try {
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file_id = H5.H5Fcreate(FILENAME, HDF5Constants.H5F_ACC_TRUNC,
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HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Create dataspace. Setting maximum size to NULL sets the maximum
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// size to be the current size.
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try {
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filespace_id = H5.H5Screate_simple(RANK, dims, null);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Create the dataset creation property list, add the gzip compression
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// filter.
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try {
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dcpl_id = H5.H5Pcreate(HDF5Constants.H5P_DATASET_CREATE);
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if (dcpl_id >= 0) {
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H5.H5Pset_deflate(dcpl_id, 9);
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// Set the chunk size.
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H5.H5Pset_chunk(dcpl_id, NDIMS, chunk_dims);
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}
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Create the dataset.
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try {
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if ((file_id >= 0) && (filespace_id >= 0) && (dcpl_id >= 0))
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dataset_id = H5.H5Dcreate(file_id, DATASETNAME,
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HDF5Constants.H5T_STD_I32LE, filespace_id, dcpl_id);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Write the data to the dataset.
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try {
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if (dataset_id >= 0)
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H5.H5Dwrite(dataset_id, HDF5Constants.H5T_NATIVE_INT,
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HDF5Constants.H5S_ALL, HDF5Constants.H5S_ALL,
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HDF5Constants.H5P_DEFAULT, dset_data);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// End access to the dataset and release resources used by it.
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try {
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if (dcpl_id >= 0)
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H5.H5Pclose(dcpl_id);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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try {
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if (dataset_id >= 0)
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H5.H5Dclose(dataset_id);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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try {
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if (filespace_id >= 0)
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H5.H5Sclose(filespace_id);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Close the file.
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try {
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if (file_id >= 0)
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H5.H5Fclose(file_id);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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}
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private static void readGzip() {
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int file_id = -1;
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int dataset_id = -1;
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int dcpl_id = -1;
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int[][] dset_data = new int[DIM_X][DIM_Y];
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// Open an existing file.
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try {
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file_id = H5.H5Fopen(FILENAME, HDF5Constants.H5F_ACC_RDONLY,
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HDF5Constants.H5P_DEFAULT);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Open an existing dataset.
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try {
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if (file_id >= 0)
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dataset_id = H5.H5Dopen(file_id, DATASETNAME);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Retrieve the dataset creation property list.
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try {
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if (dataset_id >= 0)
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dcpl_id = H5.H5Dget_create_plist(dataset_id);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Retrieve and print the filter type. Here we only retrieve the
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// first filter because we know that we only added one filter.
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try {
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if (dcpl_id >= 0) {
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// Java lib requires a valid filter_name object and cd_values
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int[] flags = { 0 };
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int[] cd_nelmts = { 1 };
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int[] cd_values = { 0 };
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String[] filter_name = { "" };
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int filter_type = -1;
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filter_type = H5.H5Pget_filter(dcpl_id, 0, flags, cd_nelmts, cd_values,
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120, filter_name);
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System.out.print("Filter type is: ");
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switch (H5Z_filter.get(filter_type)) {
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case H5Z_FILTER_DEFLATE:
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System.out.println("H5Z_FILTER_DEFLATE");
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break;
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case H5Z_FILTER_SHUFFLE:
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System.out.println("H5Z_FILTER_SHUFFLE");
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break;
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case H5Z_FILTER_FLETCHER32:
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System.out.println("H5Z_FILTER_FLETCHER32");
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break;
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case H5Z_FILTER_SZIP:
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System.out.println("H5Z_FILTER_SZIP");
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break;
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default:
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System.out.println("H5Z_FILTER_ERROR");
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}
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System.out.println();
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}
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Read the data using the default properties.
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try {
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if (dataset_id >= 0) {
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H5.H5Dread(dataset_id, HDF5Constants.H5T_NATIVE_INT,
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HDF5Constants.H5S_ALL, HDF5Constants.H5S_ALL,
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HDF5Constants.H5P_DEFAULT, dset_data);
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}
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Find the maximum value in the dataset, to verify that it was read
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// correctly.
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int max = dset_data[0][0];
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for (int indx = 0; indx < DIM_X; indx++) {
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for (int jndx = 0; jndx < DIM_Y; jndx++)
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if (max < dset_data[indx][jndx])
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max = dset_data[indx][jndx];
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}
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// Print the maximum value.
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System.out.println("Maximum value in " + DATASETNAME + " is: " + max);
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// End access to the dataset and release resources used by it.
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try {
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if (dcpl_id >= 0)
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H5.H5Pclose(dcpl_id);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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try {
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if (dataset_id >= 0)
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H5.H5Dclose(dataset_id);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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// Close the file.
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try {
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if (file_id >= 0)
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H5.H5Fclose(file_id);
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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}
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public static void main(String[] args) {
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// Check if gzip compression is available and can be used for both
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// compression and decompression. Normally we do not perform error
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// checking in these examples for the sake of clarity, but in this
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// case we will make an exception because this filter is an
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// optional part of the hdf5 library.
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if (H5Ex_D_Gzip.checkGzipFilter()) {
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H5Ex_D_Gzip.writeGzip();
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H5Ex_D_Gzip.readGzip();
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}
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}
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}
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