Read from the variables in the file

/* This is part of the netCDF package.
   Copyright 2006 University Corporation for Atmospheric Research/Unidata.
   See COPYRIGHT file for conditions of use.

   This is an example which reads some 4D pressure and
   temperatures. The data file read by this program is produced by the
   companion program pres_temp_4D_wr.java. It is intended to
   illustrate the use of the netCDF Java API.

   This example demonstrates the netCDF Java API.

   Full documentation of the netCDF Java API can be found at:
   http://www.unidata.ucar.edu/software/netcdf-java/
*/

package examples;

import ucar.nc2.Variable;
import ucar.nc2.NetcdfFile;
import ucar.ma2.ArrayFloat;
import ucar.ma2.InvalidRangeException;

import java.io.IOException;

public class Pres_temp_4D_rd {

  public static void main(String args[]) {
    final int NLVL = 2;
    final int NLAT = 6;
    final int NLON = 12;

    // These are used to construct some example data.
    final float SAMPLE_PRESSURE = 900.0f;
    final float SAMPLE_TEMP = 9.0f;
    final float START_LAT = 25.0f;
    final float START_LON = -125.0f;

    // Open the file.
    String filename = "pres_temp_4D.nc";
    NetcdfFile dataFile = null;
    try {

      dataFile = NetcdfFile.open(filename, null);

      // Get the latitude and longitude Variables.
      Variable latVar = dataFile.findVariable("latitude");
      if (latVar == null) {
        System.out.println("Cant find Variable latitude");
        return;
      }

      Variable lonVar = dataFile.findVariable("longitude");
      if (lonVar == null) {
        System.out.println("Cant find Variable longitude");
        return;
      }

      // Get the lat/lon data from the file.
      ArrayFloat.D1 latArray;
      ArrayFloat.D1 lonArray;

      latArray = (ArrayFloat.D1) latVar.read();
      lonArray = (ArrayFloat.D1) lonVar.read();


      // Check the coordinate variable data.
      for (int lat = 0; lat < NLAT; lat++)
        if (latArray.get(lat) != START_LAT + 5. * lat)
          System.err.println("ERROR incorrect value in variable latitude");

      for (int lon = 0; lon < NLON; lon++)
        if (lonArray.get(lon) != START_LON + 5. * lon)
          System.err.println("ERROR incorrect value in variable longtitude");

      // Get the pressure and temperature variables.
      Variable presVar = dataFile.findVariable("pressure");
      if (presVar == null) {
        System.out.println("Cant find Variable pressure");
        return;
      }

      Variable tempVar = dataFile.findVariable("temperature");
      if (lonVar == null) {
        System.out.println("Cant find Variable temperature");
        return;
      }

      int[] shape = presVar.getShape();
      int recLen = shape[0]; // number of times

      int[] origin = new int[4];
      shape[0] = 1; // only one rec per read

      // loop over the rec dimension
      for (int rec = 0; rec < recLen; rec++) {
        origin[0] = rec;  // read this index

        // read 3D array for that index
        ArrayFloat.D3 presArray, tempArray;

        presArray = (ArrayFloat.D3) (presVar.read(origin, shape).reduce());
        tempArray = (ArrayFloat.D3) (tempVar.read(origin, shape).reduce());


        // now checking the value
        int count = 0;
        for (int lvl = 0; lvl < NLVL; lvl++)
          for (int lat = 0; lat < NLAT; lat++)
            for (int lon = 0; lon < NLON; lon++) {
              if ((presArray.get(lvl, lat, lon) != SAMPLE_PRESSURE + count) ||
                      (tempArray.get(lvl, lat, lon) != SAMPLE_TEMP + count))
                System.err.println("ERROR incorrect value in variable pressure or temperature");
              count++;
            }
      }

      // The file is closed no matter what by putting inside a try/catch block.
    } catch (java.io.IOException e) {
      e.printStackTrace();
      return;

    } catch (InvalidRangeException e) {
      e.printStackTrace();
      return;

    } finally {
      if (dataFile != null)
        try {
          dataFile.close();
        } catch (IOException ioe) {
          ioe.printStackTrace();
        }
    }
    System.out.println("*** SUCCESS reading example file " + filename);
  }

}