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[netCDFJava #KUD-999886]: Inconsistent results from Array.getDouble()/Array.getFloat()

Hi Aaron:

the problem is that the 2 files have different scale / offsets, and its 
flipping between which one is being used. Problem is that scale/offset gets 
applied after the aggregation is done. Not sure how to fix this problem, ill 
let you know. In the meanwhile if you can write the files with same 
scale/offset that would work.

John




> Hi Aaron:
> 
> Ive reproduce the problem and ill let you know when i figure out whats up. 
> thanks for the test case.
> 
> Jon
> 
> > Hello,
> >
> > In some cases the netCDF API is returning one value (such as
> > "17.699193954467773"), and at other times it is returning another (such
> > as "17.000396728515625").  I created a Java main() to reproduce this
> > problem independently of ncWMS:
> >
> > public static void main( String[] args ) throws Exception{
> > //    GridDataset dataset = GridDataset.open(
> > "/data/nssl2dMosaic/2013/20130619/v_020500/20130619_v_020500_l_0000000.nc"
> > );
> > GridDataset dataset = GridDataset.open(
> > "/data/nssl2dMosaic/dataset.ncml" );
> > GridDatatype grid = null;
> > for( GridDatatype thisGrid : dataset.getGrids() ){
> > if( thisGrid.getName().equals( "cref" )){
> > grid = thisGrid;
> > }
> > }
> > List<Range> ranges = new ArrayList<Range>();
> > ranges.add( new Range( 0, 0 ) );
> > ranges.add( new Range( 0, 0 ) );
> > ranges.add( new Range( 638, 638 ) );
> > ranges.add( new Range( 3750, 4622 ) );
> > Array arr = grid.getVariable().read( ranges );
> > Index index = arr.getIndex();
> > index.set( new int[]{0,0,0,834} );
> > System.out.println( arr.getDouble( index ) );
> > dataset.close();
> > }
> >
> > Running this program several times will return one of two values: either
> > "17.000396728515625" or "17.699193954467773", depending on the run.
> > This main() was derived from reverse-engineering the process used by
> > ncWMS for accessing my data.  I first encountered this with netCDF API 4.2.
> >
> > Another interesting wrinkle is that if I only have the single data file
> > (the one with the value accessed by this test - commented out above) in
> > the data directory it always returns the "17.0" value.  It is only when
> > I have two or more files that match the NCML declaration that
> > occasionally it will return different values. Based on this behavior it
> > may be an NCML issue and it seems likely that the "17.0" is the correct
> > data value.  I ran this with netCDF API 4.3.1.3 I downloaded a few
> > minutes ago and it exhibited the same problem.
> >
> > The data for this test may be found under
> > http://www.ral.ucar.edu/staff/braeckel/nssl2dMosaic/.  Any thoughts on
> > what may be going on?
> >
> > Thanks,
> > Aaron
> >
> >
> 

Ticket Details
===================
Ticket ID: KUD-999886
Department: Support netCDF Java
Priority: Normal
Status: Open