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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the COPYING file, which can be found at the root of the source code *
* distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases. *
* If you do not have access to either file, you may request a copy from *
* help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/************************************************************
This example shows how to read and write data to a dataset
using a data transform expression. The program first
writes integers to a dataset using the transform
expression TRANSFORM, then closes the file. Next, it
reopens the file, reads back the data without a transform,
and outputs the data to the screen. Finally it reads the
data using the transform expression RTRANSFORM and outputs
the results to the screen.
************************************************************/
package examples.datasets;
import hdf.hdf5lib.H5;
import hdf.hdf5lib.HDF5Constants;
public class H5Ex_D_Transform {
private static String FILE = "H5Ex_D_Transform.h5";
private static String DATASET = "DS1";
private static final int DIM_X = 4;
private static final int DIM_Y = 7;
private static String TRANSFORM = "x+1";
private static String RTRANSFORM = "x-1";
private static void writeData() {
long file_id = -1;
long filespace_id = -1;
long dataset_id = -1;
long dxpl_id = -1;
long[] dims = { DIM_X, DIM_Y };
int[][] dset_data = new int[DIM_X][DIM_Y];
// Initialize data.
for (int i = 0; i < DIM_X; i++)
for (int j = 0; j < DIM_Y; j++)
dset_data[i][j] = i * j - j;
// Output the data to the screen.
System.out.println("Original Data:");
for (int i = 0; i < DIM_X; i++) {
System.out.print(" [");
for (int j = 0; j < DIM_Y; j++)
System.out.print(" " + dset_data[i][j] + " ");
System.out.println("]");
}
// Create a new file using the default properties.
try {
file_id = H5.H5Fcreate(FILE, HDF5Constants.H5F_ACC_TRUNC, HDF5Constants.H5P_DEFAULT,
HDF5Constants.H5P_DEFAULT);
}
catch (Exception e) {
e.printStackTrace();
}
// Create dataspace. Setting maximum size to NULL sets the maximum
// size to be the current size.
try {
filespace_id = H5.H5Screate_simple(2, dims, null);
}
catch (Exception e) {
e.printStackTrace();
}
// Create the dataset transfer property list and define the transform expression.
try {
dxpl_id = H5.H5Pcreate(HDF5Constants.H5P_DATASET_XFER);
if (dxpl_id >= 0)
H5.H5Pset_data_transform(dxpl_id, TRANSFORM);
}
catch (Exception e) {
e.printStackTrace();
}
// Create the dataset using the default properties. Unfortunately we must save as
// a native type or the transform operation will fail.
try {
if ((file_id >= 0) && (filespace_id >= 0))
dataset_id = H5.H5Dcreate(file_id, DATASET, HDF5Constants.H5T_NATIVE_INT, filespace_id,
HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT);
}
catch (Exception e) {
e.printStackTrace();
}
// Write the data to the dataset using the dataset transfer property list.
try {
if ((dataset_id >= 0) && (dxpl_id >= 0))
H5.H5Dwrite(dataset_id, HDF5Constants.H5T_NATIVE_INT, HDF5Constants.H5S_ALL, HDF5Constants.H5S_ALL,
dxpl_id, dset_data);
}
catch (Exception e) {
e.printStackTrace();
}
// End access to the dataset and release resources used by it.
try {
if (dxpl_id >= 0)
H5.H5Pclose(dxpl_id);
}
catch (Exception e) {
e.printStackTrace();
}
try {
if (dataset_id >= 0)
H5.H5Dclose(dataset_id);
}
catch (Exception e) {
e.printStackTrace();
}
try {
if (filespace_id >= 0)
H5.H5Sclose(filespace_id);
}
catch (Exception e) {
e.printStackTrace();
}
// Close the file.
try {
if (file_id >= 0)
H5.H5Fclose(file_id);
}
catch (Exception e) {
e.printStackTrace();
}
}
private static void readData() {
long file_id = -1;
long dataset_id = -1;
long dxpl_id = -1;
int[][] dset_data = new int[DIM_X][DIM_Y];
// Open an existing file using the default properties.
try {
file_id = H5.H5Fopen(FILE, HDF5Constants.H5F_ACC_RDONLY, HDF5Constants.H5P_DEFAULT);
}
catch (Exception e) {
e.printStackTrace();
}
// Open an existing dataset using the default properties.
try {
if (file_id >= 0)
dataset_id = H5.H5Dopen(file_id, DATASET, HDF5Constants.H5P_DEFAULT);
}
catch (Exception e) {
e.printStackTrace();
}
// Read the data using the default properties.
try {
if (dataset_id >= 0)
H5.H5Dread(dataset_id, HDF5Constants.H5T_NATIVE_INT, HDF5Constants.H5S_ALL, HDF5Constants.H5S_ALL,
HDF5Constants.H5P_DEFAULT, dset_data);
}
catch (Exception e) {
e.printStackTrace();
}
// Output the data to the screen.
System.out.println("Data as written with transform '" + TRANSFORM + "'");
for (int i = 0; i < DIM_X; i++) {
System.out.print(" [");
for (int j = 0; j < DIM_Y; j++)
System.out.print(" " + dset_data[i][j] + " ");
System.out.println("]");
}
// Create the dataset transfer property list and define the transform expression.
try {
dxpl_id = H5.H5Pcreate(HDF5Constants.H5P_DATASET_XFER);
if (dxpl_id >= 0)
H5.H5Pset_data_transform(dxpl_id, RTRANSFORM);
}
catch (Exception e) {
e.printStackTrace();
}
// Read the data using the dataset transfer property list.
try {
if ((dataset_id >= 0) && (dxpl_id >= 0))
H5.H5Dread(dataset_id, HDF5Constants.H5T_NATIVE_INT, HDF5Constants.H5S_ALL, HDF5Constants.H5S_ALL,
dxpl_id, dset_data);
}
catch (Exception e) {
e.printStackTrace();
}
// Output the data to the screen.
System.out.println("Data as written with transform '" + TRANSFORM + "' and read with transform '"
+ RTRANSFORM + "'");
for (int i = 0; i < DIM_X; i++) {
System.out.print(" [");
for (int j = 0; j < DIM_Y; j++)
System.out.print(" " + dset_data[i][j] + " ");
System.out.println("]");
}
// Close and release resources.
try {
if (dxpl_id >= 0)
H5.H5Pclose(dxpl_id);
}
catch (Exception e) {
e.printStackTrace();
}
try {
if (dataset_id >= 0)
H5.H5Dclose(dataset_id);
}
catch (Exception e) {
e.printStackTrace();
}
try {
if (file_id >= 0)
H5.H5Fclose(file_id);
}
catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
H5Ex_D_Transform.writeData();
H5Ex_D_Transform.readData();
}
}
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