[netcdf-java] BUG: Rectilinear sub-grid miscalculates coord edges

• To: Java NetCDF <netcdf-java@xxxxxxxxxxxxxxxx>
• Subject: [netcdf-java] BUG: Rectilinear sub-grid miscalculates coord edges
• From: Christian Ward-Garrison <cwardgar@xxxxxxxx>
• Date: Tue, 04 May 2010 20:24:20 -0600

foo.ncml:

<?xml version="1.0" encoding="UTF-8"?>
<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
    <dimension name="time" length="4" />
    <dimension name="lat"  length="4"  />
    <dimension name="lon"  length="4"  />
    <dimension name="bnds" length="2"  />

    <variable name="time" shape="time" type="double">
        <attribute name="units" type="String" value="days since 1850-01-01" />
        <attribute name="calendar" type="String" value="standard" />
        <attribute name="bounds" type="String" value="time_bnds" />
        <values>15.5 45.0 74.5 105.0</values>
    </variable>

    <variable name="time_bnds" shape="time bnds" type="double">
        <values>0.0 31.0 31.0 59.0 59.0 90.0 90.0 120.0</values>
    </variable>

    <variable name="lat" shape="lat" type="double">
        <attribute name="units" type="String" value="degrees_north" />
        <attribute name="bounds" type="String" value="lat_bnds" />
        <values>-54 9 54 81</values>
    </variable>

    <variable name="lat_bnds" shape="lat bnds" type="double">
        <values>-90 -18 -18 36 36 72 72 90</values>
    </variable>

    <variable name="lon" shape="lon" type="double">
        <attribute name="units" type="String" value="degrees_east" />
        <attribute name="bounds" type="String" value="lon_bnds" />
        <values>18 72 162 288</values>
    </variable>

    <variable name="lon_bnds" shape="lon bnds" type="double">
        <values>0 36 36 108 108 216 216 360</values>
    </variable>

    <variable name="foo" shape="time lat lon" type="float">
        <values start="1.0" increment="1.0" />
    </variable>
</netcdf>


Foo.java:

    public static void main(String[] args) throws IOException, 
InvalidRangeException {
        File fooNcmlFile = new File("foo.ncml");
        NetcdfDataset fooDataset = 
NetcdfDataset.openDataset(fooNcmlFile.getAbsolutePath());

        try {
            GridDataset fooGridDataset = new GridDataset(fooDataset);
            GridDatatype fooGrid = fooGridDataset.findGridDatatype("foo");

            CoordinateAxis1D fooTimeAxis = 
fooGrid.getCoordinateSystem().getTimeAxis1D();
            CoordinateAxis1D fooLatAxis  = (CoordinateAxis1D) 
fooGrid.getCoordinateSystem().getYHorizAxis();
            CoordinateAxis1D fooLonAxis  = (CoordinateAxis1D) 
fooGrid.getCoordinateSystem().getXHorizAxis();

            // Expected: [0.0, 31.0, 59.0, 90.0, 120.0]
            // Actual:   [0.0, 31.0, 59.0, 90.0, 120.0]
            System.out.println(Arrays.toString(fooTimeAxis.getCoordEdges()));

            // Expected: [-90.0, -18.0, 36.0, 72.0, 90.0]
            // Actual:   [-90.0, -18.0, 36.0, 72.0, 90.0]
            System.out.println(Arrays.toString(fooLatAxis.getCoordEdges()));

            // Expected: [0.0, 36.0, 108.0, 216.0, 360.0]
            // Actual:   [0.0, 36.0, 108.0, 216.0, 360.0]
            System.out.println(Arrays.toString(fooLonAxis.getCoordEdges()));


            Range middleRange = new Range(1, 2);
            GridDatatype fooSubGrid = fooGrid.makeSubset(null, null, 
middleRange, null, middleRange, middleRange);

            CoordinateAxis1D fooSubTimeAxis = 
fooSubGrid.getCoordinateSystem().getTimeAxis1D();
            CoordinateAxis1D fooSubLatAxis  = (CoordinateAxis1D) 
fooSubGrid.getCoordinateSystem().getYHorizAxis();
            CoordinateAxis1D fooSubLonAxis  = (CoordinateAxis1D) 
fooSubGrid.getCoordinateSystem().getXHorizAxis();

            // Expected: [31.0, 59.0, 90.0]
            // Actual:   [30.25, 59.75, 89.25]
            System.out.println(Arrays.toString(fooSubTimeAxis.getCoordEdges()));

            // Expected: [-18.0, 36.0, 72.0]
            // Actual:   [-13.5, 31.5, 76.5]
            System.out.println(Arrays.toString(fooSubLatAxis.getCoordEdges()));

            // Expected: [36.0, 108.0, 216.0]
            // Actual:   [27.0, 117.0, 207.0]
            System.out.println(Arrays.toString(fooSubLonAxis.getCoordEdges()));
        } finally {
            fooDataset.close();
        }
    }

• Follow-Ups:
  • Re: [netcdf-java] BUG: Rectilinear sub-grid miscalculates coord edges
    • From: John Caron