Re: A bug with Lat/Lon grids...

• To: Rob Weingruber <weingrub@xxxxxxxxxxxx>
• Subject: Re: A bug with Lat/Lon grids...
• From: John Caron <caron@xxxxxxxxxxxxxxxx>
• Date: Mon, 26 Feb 2007 10:09:04 -0700

Hi Rob: thanks, I found this bug and will patch 2.2.18. Still looking at the 
gini stride problem.

Rob Weingruber wrote:

Hi John -

Looks like I might have found another bug, this time with server-side Netcdf data

that's natively in a lat/lon grid (seems to work if non-LL grid).

The method on GridCoordSys:

public List getRangesFromLatLonRect(LatLonRect rect)

has this snippet of code near the beginning of the method:

    if (isLatLon()) {

minx = getMinOrMaxLon( llpt.getLongitude(), ulpt.getLongitude(), true);

      miny = Math.min( llpt.getLatitude(), lrpt.getLatitude());

maxx = getMinOrMaxLon( urpt.getLongitude(), lrpt.getLongitude(), false);

      maxy = Math.min( ulpt.getLatitude(), urpt.getLatitude());

    } else {...}

If I try to geoGrid.subset(....) with a lat/lon bbox that is *bigger* than the data (say I zooom waaaay out, strides = 1), the above code will return, say, a minx and maxx that would extend outside of the data. That's good (i think). But then a few lines later, the following

code will have problems:

if ((xaxis instanceof CoordinateAxis1D) && (yaxis instanceof CoordinateAxis1D)) {

      CoordinateAxis1D xaxis1 = (CoordinateAxis1D) xaxis;
      CoordinateAxis1D yaxis1 = (CoordinateAxis1D) yaxis;

      int minxIndex = xaxis1.findCoordElementBounded(minx);
      int minyIndex = yaxis1.findCoordElementBounded(miny);

      int maxxIndex = xaxis1.findCoordElementBounded(maxx);
      int maxyIndex = yaxis1.findCoordElementBounded(maxy);

      ArrayList list = new ArrayList();
      try {

list.add(new Range(Math.min(minyIndex, maxyIndex), Math.max(minyIndex, maxyIndex))); list.add(new Range(Math.min(minxIndex, maxxIndex), Math.max(minxIndex, maxxIndex)));

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


If the minx/maxx etc fall outside of the data, then for example,
xaxis1.findCoordElementBounded(minx) might return -1, in which
case the new Range(....) will throw an exception.

Havent tried non-1 strides yet...

Here's the url (with tunnel ;-( that I am using:

http://www.rap.ucar.edu/projects/rdwx_mdss/thredds.php/dodsC/data/decIR

geoGridName = "micron11"

And an example data file is attached.

;-)  Thanks for listening, and whatever you can do ;-))

Enjoying the conference??

;-)