hdf5/HDF5Examples/JAVA/H5T/H5Ex_T_Float.java

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 * Copyright by The HDF Group.                                               *
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 * help@hdfgroup.org.                                                        *
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/************************************************************
  This example shows how to read and write integer datatypes
  to a dataset.  The program first writes integers to a
  dataset with a dataspace of DIM0xDIM1, then closes the
  file.  Next, it reopens the file, reads back the data, and
  outputs it to the screen.
 ************************************************************/

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.util.Locale;

import hdf.hdf5lib.H5;
import hdf.hdf5lib.HDF5Constants;

public class H5Ex_T_Float {
    private static String FILENAME    = "H5Ex_T_Float.h5";
    private static String DATASETNAME = "DS1";
    private static final int DIM0     = 4;
    private static final int DIM1     = 7;
    private static final int RANK     = 2;

    private static void CreateDataset()
    {
        long file_id         = HDF5Constants.H5I_INVALID_HID;
        long dataspace_id    = HDF5Constants.H5I_INVALID_HID;
        long dataset_id      = HDF5Constants.H5I_INVALID_HID;
        long[] dims          = {DIM0, DIM1};
        double[][] dset_data = new double[DIM0][DIM1];

        // Initialize data.
        for (int indx = 0; indx < DIM0; indx++)
            for (int jndx = 0; jndx < DIM1; jndx++) {
                dset_data[indx][jndx] = indx / (jndx + 0.5) + jndx;
            }

        // Create a new file using default properties.
        try {
            file_id = H5.H5Fcreate(FILENAME, 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 {
            dataspace_id = H5.H5Screate_simple(RANK, dims, null);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Create the dataset and write the floating point data to it. In
        // this example we will save the data as 64 bit little endian IEEE
        // floating point numbers, regardless of the native type. The HDF5
        // library automatically converts between different floating point
        // types.
        try {
            if ((file_id >= 0) && (dataspace_id >= 0))
                dataset_id = H5.H5Dcreate(file_id, DATASETNAME, HDF5Constants.H5T_IEEE_F64LE, dataspace_id,
                                          HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT,
                                          HDF5Constants.H5P_DEFAULT);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Write the data to the dataset.
        try {
            if (dataset_id >= 0)
                H5.H5Dwrite(dataset_id, HDF5Constants.H5T_NATIVE_DOUBLE, HDF5Constants.H5S_ALL,
                            HDF5Constants.H5S_ALL, HDF5Constants.H5P_DEFAULT, dset_data);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // End access to the dataset and release resources used by it.
        try {
            if (dataset_id >= 0)
                H5.H5Dclose(dataset_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Terminate access to the data space.
        try {
            if (dataspace_id >= 0)
                H5.H5Sclose(dataspace_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 ReadDataset()
    {
        long file_id      = HDF5Constants.H5I_INVALID_HID;
        long dataspace_id = HDF5Constants.H5I_INVALID_HID;
        long dataset_id   = HDF5Constants.H5I_INVALID_HID;
        long[] dims       = {DIM0, DIM1};
        double[][] dset_data;

        // Open an existing file.
        try {
            file_id = H5.H5Fopen(FILENAME, HDF5Constants.H5F_ACC_RDONLY, HDF5Constants.H5P_DEFAULT);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Open an existing dataset.
        try {
            if (file_id >= 0)
                dataset_id = H5.H5Dopen(file_id, DATASETNAME, HDF5Constants.H5P_DEFAULT);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Get dataspace and allocate memory for read buffer.
        try {
            if (dataset_id >= 0)
                dataspace_id = H5.H5Dget_space(dataset_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        try {
            if (dataspace_id >= 0)
                H5.H5Sget_simple_extent_dims(dataspace_id, dims, null);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Allocate array of pointers to two-dimensional arrays (the
        // elements of the dataset.
        dset_data = new double[(int)dims[0]][(int)(dims[1])];

        // Read data.
        try {
            if (dataset_id >= 0)
                H5.H5Dread(dataset_id, HDF5Constants.H5T_NATIVE_DOUBLE, HDF5Constants.H5S_ALL,
                           HDF5Constants.H5S_ALL, HDF5Constants.H5P_DEFAULT, dset_data);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Output the data to the screen.
        DecimalFormat df = new DecimalFormat("#,##0.0000", new DecimalFormatSymbols(Locale.US));
        System.out.println(DATASETNAME + ":");
        for (int indx = 0; indx < dims[0]; indx++) {
            System.out.print(" [");
            for (int jndx = 0; jndx < dims[1]; jndx++) {
                System.out.print(" " + df.format(dset_data[indx][jndx]));
            }
            System.out.println("]");
        }
        System.out.println();

        // End access to the dataset and release resources used by it.
        try {
            if (dataset_id >= 0)
                H5.H5Dclose(dataset_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Terminate access to the data space.
        try {
            if (dataspace_id >= 0)
                H5.H5Sclose(dataspace_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Close the file.
        try {
            if (file_id >= 0)
                H5.H5Fclose(file_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args)
    {
        H5Ex_T_Float.CreateDataset();
        // Now we begin the read section of this example. Here we assume
        // the dataset and array have the same name and rank, but can have
        // any size. Therefore we must allocate a new array to read in
        // data using malloc().
        H5Ex_T_Float.ReadDataset();
    }
}