/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
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* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
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package ucar.nc2.dataset;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;
import ucar.nc2.*;
import ucar.nc2.constants.CDM;
import ucar.ma2.*;
import java.io.IOException;
public class TestScaleOffset {
@Rule
public TemporaryFolder tempFolder = new TemporaryFolder();
@Test
public void testWrite() throws Exception {
String filename = tempFolder.newFile("scaleOffset.nc").getAbsolutePath();
ArrayDouble unpacked;
MAMath.ScaleOffset so;
Array packed;
try (NetcdfFileWriteable ncfile = NetcdfFileWriteable.createNew(filename)) {
// define dimensions
Dimension latDim = ncfile.addDimension("lat", 200);
Dimension lonDim = ncfile.addDimension("lon", 300);
int n = lonDim.getLength();
// create an array
unpacked = new ArrayDouble.D2(latDim.getLength(), lonDim.getLength());
Index ima = unpacked.getIndex();
for (int i = 0; i < latDim.getLength(); i++) {
for (int j = 0; j < lonDim.getLength(); j++) {
unpacked.setDouble(ima.set(i, j), (i * n + j) + 30.0);
}
}
boolean isUnsigned = true;
double missingValue = -9999;
int nbits = 16;
// convert to packed form
so = MAMath.calcScaleOffsetSkipMissingData(unpacked, missingValue, nbits, isUnsigned);
ncfile.addVariable("unpacked", DataType.DOUBLE, "lat lon");
ncfile.addVariable("packed", DataType.SHORT, "lat lon");
if (isUnsigned) {
ncfile.addVariableAttribute("packed", CDM.UNSIGNED, "true");
}
//ncfile.addVariableAttribute("packed", CDM.MISSING_VALUE, new Short( (short) -9999));
ncfile.addVariableAttribute("packed", CDM.SCALE_FACTOR, so.scale);
ncfile.addVariableAttribute("packed", "add_offset", so.offset);
// create the file
ncfile.create();
ncfile.write("unpacked", unpacked);
packed = MAMath.convert2packed(unpacked, missingValue, nbits, isUnsigned, DataType.SHORT);
ncfile.write("packed", packed);
}
Array readPacked;
// read the packed form, compare to original
try (NetcdfFile ncfileRead = NetcdfFile.open(filename)) {
Variable v = ncfileRead.findVariable("packed");
assert v != null;
readPacked = v.read();
ucar.unidata.util.test.CompareNetcdf.compareData(readPacked, packed);
}
Array readEnhanced;
// read the packed form, enhance using scale/offset, compare to original
try (NetcdfDataset ncd = NetcdfDataset.openDataset(filename)) {
Variable vs = ncd.findVariable("packed");
assert vs != null;
readEnhanced = vs.read();
//TestCompare.compareData(readEnhanced, unpacked);
closeEnough(packed, unpacked, readEnhanced, 1.0 / so.scale);
}
Array cnvertPacked = MAMath.convert2Unpacked(readPacked, so);
//TestCompare.compareData(readUnpacked, unpacked);
closeEnough(packed, cnvertPacked, readEnhanced, 1.0 / so.scale);
doSubset(filename);
}
void closeEnough(Array packed, Array data1, Array data2, double close) {
IndexIterator iterp = packed.getIndexIterator();
IndexIterator iter1 = data1.getIndexIterator();
IndexIterator iter2 = data2.getIndexIterator();
while (iter1.hasNext()) {
double v1 = iter1.getDoubleNext();
double v2 = iter2.getDoubleNext();
double p = iterp.getDoubleNext();
double diff = Math.abs(v1 - v2);
assert (diff < close) : v1 + " != " + v2 + " index=" + iter1+" packed="+p;
//System.out.println(v1 + " == " + v2 + " index=" + iter1+" packed="+p);
}
}
// check section of scale/offset only applies it once
private void doSubset(String filename) throws IOException, InvalidRangeException {
// read the packed form, enhance using scale/offset, compare to original
try (NetcdfDataset ncd = NetcdfDataset.openDataset(filename)) {
Variable vs = ncd.findVariable("packed");
assert vs != null;
Section s = new Section().appendRange(1, 1).appendRange(1, 1);
Array readEnhanced = vs.read(s);
NCdumpW.printArray(readEnhanced);
Variable sec = vs.section(s);
Array readSection = sec.read();
NCdumpW.printArray(readSection);
ucar.unidata.util.test.CompareNetcdf.compareData(readEnhanced, readSection);
}
}
}