Dear all!

I would like to ask two questions: one concerning `imshow`

with

the Robinson projection and the second about the latitude limits for

the same map projection.

First, I am trying to make a Robinson projection map using `imshow`

instead of `contourf`

as described in the `Basemap`

documentation. I modified the script as follows:

`#----------------------------------------------------------------------`

`from matplotlib.toolkits.basemap import Basemap, shiftgrid`

`from pylab import load, meshgrid, title, arange, show, cm, pi`

`#`

`# read in topo data (on a regular lat/lon grid)`

`etopo = load('etopo20data.gz')`

`lons = load('etopo20lons.gz')`

`lats = load('etopo20lats.gz')`

`#`

`# create Basemap instance for Robinson projection.`

`m = Basemap(projection='robin',lon_0=0.5*(lons[0]+lons[-1]))`

`#`

`# compute native map projection coordinates for lat/lon grid.`

`etopo, lons = shiftgrid(180., etopo, lons, start=False)`

`x, y = m(*meshgrid(lons,lats))`

`dx = 2.*pi*m.rmajor/len(lons)`

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

`dat, x, y = m.transform_scalar(etopo, lons, lats, nx, ny, returnxy=True)`

`#`

`# make filled contour plot.`

`im = m.imshow(dat, cmap=cm.jet)`

`m.drawcoastlines() # draw coastlines`

`m.drawmapboundary() # draw a line around the map region`

`m.drawparallels(arange(-90.,120.,30.),labels=[1,0,0,0]) # draw parallels`

`m.drawmeridians(arange(0.,420.,60.),labels=[0,0,0,1]) # draw meridians`

`title('Robinson Projection') # add a title`

`show()`

`#----------------------------------------------------------------------`

The result looks as I would expect, except that some data is plot

outside of the map boundaries. Using another projection as the

Orthographic for example, this problem doesn’t happen. Am I doing

something wrong?

Second, I work with Topex/POSEIDON and Jason-1 sea surface height

anomalies datasets where the latitudes range from about 67.5S to 67.5N.

Outside these limits hopefully its blank, as anyone would expect.

Aesthetically I find it more appealing if I could limit my map

boundaries to these limits, or even lower limits if I zoom the

equatorial region. Has anyone ever tried to do this?

Thank’s in advance and kind regards,

Sebastian