[Matplotlib-users] basemap, transform_scalar question

[John [H2O] <was...@gm...>]

I'm trying to 'automate' a few components within basemap. I have a pretty
complicated, and assuredly poorly written, set of functions that allow me to
'dynamically' plot a grid of data (lon,lat).

Here is one section where I try to deal with transforming the data based on
the projection. 'data' is a grid, often of size 720x360 or 720x180,
representing full globe or hemisphere at 0.5 degree resolution. 'outlon0',
outlat0', and 'd*out' are the llcrnr coordinates and step. 'transform' is an
option, that is set to True by default:

1680     ## set up transformations for the data array 
1681     if m.projection not in ['cyl','merc','mill']:
1682         lats = np.arange( outlat0, ( outlat0 + ( numygrid*dyout ) ),
dyout )[:-1]
1683         lons = np.arange( outlon0, ( outlon0 + ( numxgrid*dxout ) ),
dxout )[:-1]
1684         data = data[:-1,:-1]
1685     else:
1686         lats = np.arange( outlat0, ( outlat0 + ( numygrid*dyout ) ),
dyout )
1687         lons = np.arange( outlon0, ( outlon0 + ( numxgrid*dxout ) ),
dxout )
1688 
1689     ## transform to nx x ny regularly spaced native projection grid
1690     if transform:
1691         dx = 2.*np.pi*m.rmajor/len(lons)
1692         nx = int((m.xmax-m.xmin)/dx)+1; ny = int((m.ymax-m.ymin)/dx)+1
1693         if nx is 1:
1694             topodat = data
1695         else:
1696             topodat = m.transform_scalar(data,lons,lats,nx,ny)
1697     else:
1698         topodat = data

The problem is, when I use the approach with a 'cyl' grid, then subsequently
try to draw the lsmask, I get a failure. Is this approach incorrect? I had
to use the if nx is 1 statement because it was crashing with zero division
error in some cases.

Thanks.
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