H5ObjectEx_T_Float.java

/************************************************************
  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.
 ************************************************************/

package datatypes;

import java.text.DecimalFormat;

import hdf.object.Datatype;
import hdf.object.FileFormat;
import hdf.object.h5.H5Datatype;
import hdf.object.h5.H5File;
import hdf.object.h5.H5ScalarDS;

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

public class H5ObjectEx_T_Float {
    private static String FILENAME    = "H5ObjectEx_T_Float.h5";
    private static String DATASETNAME = "DS1";
    private static final int DIM0     = 4;
    private static final int DIM1     = 7;

    private static void CreateDataset()
    {
        H5File file          = null;
        H5ScalarDS dset      = null;
        long dataset_id      = -1;
        long[] dims          = {DIM0, DIM1};
        double[][] dset_data = new double[DIM0][DIM1];
        H5Datatype typeFloat = null;

        // 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 = new H5File(FILENAME, FileFormat.CREATE);
            file.open();
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Create the base datatype.
        try {
            typeFloat = new H5Datatype(Datatype.CLASS_FLOAT, 8, Datatype.ORDER_LE, Datatype.NATIVE);
        }
        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 {
            dset = (H5ScalarDS)file.createScalarDS(DATASETNAME, null, typeFloat, dims, null, null, 0, null);
            dataset_id = dset.open();
        }
        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)
                dset.close(dataset_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Close the file.
        try {
            file.close();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static void ReadDataset()
    {
        H5File file       = null;
        H5ScalarDS dset   = null;
        long dataspace_id = -1;
        long dataset_id   = -1;
        long[] dims       = {DIM0, DIM1};
        double[][] dset_data;

        // Open an existing file.
        try {
            file = new H5File(FILENAME, FileFormat.READ);
            file.open();
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Open an existing dataset.
        try {
            dset       = (H5ScalarDS)file.get(DATASETNAME);
            dataset_id = dset.open();
        }
        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");
        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)
                dset.close(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 {
            file.close();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args)
    {
        H5ObjectEx_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().
        H5ObjectEx_T_Float.ReadDataset();
    }
}