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drawlsmask not working for rotpole

Open razcore-rad opened this issue 11 years ago • 1 comments

Now that I played with 'rotpole' a bit... I also found that dralsmask fails with ZeroDivisionError. This is the full traceback:

---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)
<ipython-input-79-0ba416c748fa> in <module>()
----> 1 m.drawlsmask(resolution='c')

/home/razvan/.local/lib/python3.4/site-packages/mpl_toolkits/basemap/__init__.py in drawlsmask(self, land_color, ocean_color, lsmask, lsmask_lons, lsmask_lats, lakes, resolution, grid, **kwargs)
   3934         # to a rectangular map projection grid.
   3935             mask,x,y = self.transform_scalar(lsmask,lsmask_lons,-> 3936                        lsmask_lats,nx,ny,returnxy=True,order=0,masked=255)
   3937             lsmask_lats.dtype
   3938             # for these projections, points outside the projection

/home/razvan/.local/lib/python3.4/site-packages/mpl_toolkits/basemap/__init__.py in transform_scalar(self, datin, lons, lats, nx, ny, returnxy, checkbounds, order, masked)
   2961                 raise ValueError('grid must be shifted so that lons are monotonically increasing and fit in range -180,+180 (see shiftgrid function)')
   2962         if returnxy:
-> 2963             lonsout, latsout, x, y = self.makegrid(nx,ny,returnxy=True)
   2964         else:
   2965             lonsout, latsout = self.makegrid(nx,ny)

/home/razvan/.local/lib/python3.4/site-packages/mpl_toolkits/basemap/__init__.py in makegrid(self, nx, ny, returnxy)
   1172         If ``returnxy = True``, the x,y values of the grid are returned also.
   1173         """
-> 1174         return self.projtran.makegrid(nx,ny,returnxy=returnxy)
   1175 
   1176     def _readboundarydata(self,name,as_polygons=False):

/home/razvan/.local/lib/python3.4/site-packages/mpl_toolkits/basemap/proj.py in makegrid(self, nx, ny, returnxy)
    332         if returnxy=True, the x,y values of the grid are returned also.
    333         """
--> 334         dx = (self.urcrnrx-self.llcrnrx)/(nx-1)
    335         dy = (self.urcrnry-self.llcrnry)/(ny-1)
    336         x = self.llcrnrx+dx*np.indices((ny,nx),np.float32)[1,:,:]

ZeroDivisionError: float division by zero

I figured it's because of this:

nx = int((self.xmax-self.xmin)/dx)+1; ny = int((self.ymax-self.ymin)/dx)+1

here self.xmax, self.xmin, ... are used incorrectly for 'rotpole' giving nx == ny == 1.

I tried changing line 3928:

if self.projection == 'cyl':

to

if self.projection == 'cyl' or self.projection == 'rotpole':

with the effect of producing a nice pattern :) but no land sea mask unfortunately... so the issue is a bit dipper, but I don't have time to investigate now...

Edit: on version 1.0.7

razcore-rad avatar May 23 '14 23:05 razcore-rad

I have the same problem for merc projection with any of the external sources of background such as bluemarble etc. Have you by any chance, found the general error?

ghost avatar Jan 30 '20 13:01 ghost