/* 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 surface pressure and
   temperatures. The data file read by this program is produced
   companion program sfc_pres_temp_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/
*/

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

import java.io.IOException;

public class Sfc_pres_temp_rd {



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

        // These are used to calculate the values we expect to find.
        final float SAMPLE_PRESSURE = 900f;
        final float SAMPLE_TEMP = 9.0f;
        final float START_LAT = 25.0f;
        final float START_LON = -125.0f;

        // These will hold our pressure and temperature data.
        float [][] presIn = new float[NLAT][NLON];
        float [][] tempIn = new float[NLAT][NLON];

        // These will hold our latitudes and longitudes.
        float [] latsIn = new float[NLAT];
        float [] lonsIn = new float[NLON];


        // Open the file and check to make sure it's valid.
        String filename = "sfc_pres_temp.nc";
        NetcdfFile dataFile = null;

        try {

            dataFile = NetcdfFileCache.acquire(filename, null);

            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;
            }


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

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


            if(latVar.getDimensions().size() != 1) {
              System.out.println(" fail to get the dimensions of variable latitude");
                return;
            }
            if(presVar.getDimensions().size() != 2) {
               System.out.println(" fail to get the dimensions of variable pressure");
                return;
            }

            // Read the latitude and longitude coordinate variables into arrays
            // latsIn and lonsIn.

            ArrayFloat.D1 latArray;
            ArrayFloat.D1 lonArray;

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

            int[] shape = latArray.getShape();
            for (int i=0; i<shape[0]; i++) {
                latsIn[i] = latArray.get(i);
            }

            shape = lonArray.getShape();
            for (int j=0; j<shape[0]; j++) {
                lonsIn[j] = lonArray.get(j);
            }

            // Check the coordinate variable data.
            for(int lat = 0; lat < NLAT; lat++)
              if (latsIn[lat] != START_LAT + 5. * lat)
                  System.err.println("ERROR reading variable latitude");

            // Check longitude values.
            for (int lon = 0; lon < NLON; lon++)
              if (lonsIn[lon] != START_LON + 5. * lon)
                 System.err.println("ERROR reading variable longitude");


            // Read the data. Since we know the contents of the file we know
            // that the data arrays in this program are the correct size to
            // hold all the data.
            ArrayFloat.D2 presArray, tempArray;

            presArray = (ArrayFloat.D2)presVar.read();
            tempArray = (ArrayFloat.D2)tempVar.read();

            int [] shape1 = presArray.getShape();

            for (int i=0; i<shape1[0]; i++) {
              for (int j=0; j<shape1[1]; j++) {
                presIn[i][j] = presArray.get(i,j);
                tempIn[i][j] = tempArray.get(i,j);
              }
            }


            // Check the data.
            for (int lat = 0; lat < NLAT; lat++)
              for (int lon = 0; lon < NLON; lon++)
                if (presIn[lat][lon] != SAMPLE_PRESSURE + (lon * NLAT + lat)
                 || tempIn[lat][lon] != SAMPLE_TEMP + .25 * (lon * NLAT + lat))
                 System.err.println("ERROR reading variable pressure or temperature");

            // Each of the netCDF variables has a "units" attribute. Let's read
            // them and check them.

            if(!latVar.findAttributeIgnoreCase("units").getStringValue().equalsIgnoreCase("degrees_north"))
                  System.err.println("ERROR reading variable latitude units");

            if(!lonVar.findAttributeIgnoreCase("units").getStringValue().equalsIgnoreCase("degrees_east"))
                  System.err.println("ERROR reading variable longitude units");

            if(!presVar.findAttributeIgnoreCase("units").getStringValue().equalsIgnoreCase("hPa"))
                  System.err.println("ERROR reading variable pressure units");

            if(!tempVar.findAttributeIgnoreCase("units").getStringValue().equalsIgnoreCase("celsius"))
                  System.err.println("ERROR reading variable temperature units");


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