Re: [Matplotlib-users] basemap: pcolormesh plot is blank; pcolor plot works

[Benjamin R. <ben...@ou...>]

I am getting something, but the speckled stuff is all on one side, and all
monochromatic for most of the pcolormesh plot. I am using basemap 1.0.7 and
a development version of matplotlib. Your code looks correct, so I don't
know what is wrong. Probably worth filing a bug report:
https://github.com/matplotlib/basemap/issues

Ben Root

On Mon, Dec 8, 2014 at 7:24 PM, Timothy W. Hilton <th...@uc...>
wrote:

> Hello,
>
> I am experiencing strange behavior using mpl_toolkits.basemap.Basemap.
> My understanding is that pcolormesh is faster than pcolor, and thus
> preferable.  Here is a minimal example (below) where I get a different
> plot from pcolormesh than from pcolor.
>
> On two systems (mac os x 10.9.5; Ubuntu 11.04 (GNU/Linux 2.6.32.28
> x86_64); basemap 1.0.7 on the mac and 1.0.8 on the Ubuntu machine; both
> using matplotlib 1.4.2) I get the expected grid of random colors from
> pcolor, but a monochrome plot from pcolormesh.
>
> Is this expected?  Are there circumstances in which I should be using
> pcolor instead of pcolormesh?  Is this a bug in matplotlib or in
> basemap?
>
> Many thanks!
>
> Tim
>
> --
>
> Timothy W. Hilton
> Assistant Project Scientist
> School of Engineering
> University of California, Merced
> th...@uc...
>
> #==================================================
> # minimal example
>
> import matplotlib.pyplot as plt
> from mpl_toolkits.basemap import Basemap
> import numpy as np
>
> def setup_map(ax):
>
>     m = Basemap(width=8.0e6,
>                 height=6.5e6,
>                 projection='aeqd',
>                 lat_0=54,
>                 lon_0=-105,
>                 resolution='l',
>                 area_thresh=1000,
>                 rsphere=6371007.181000,
>                 fix_aspect=True,
>                 ax=ax)
>     m.drawcoastlines()
>     m.drawcountries()
>     m.drawstates()
>     return(m)
>
> # create pseudo-data with longitudes and latitudes
> lon, lat = np.meshgrid(np.arange(-180, 180),
>                        np.arange(90, -90, -1))
> data = np.random.rand(*lon.shape) * 100
>
> # two-panel figure
> fig, ax = plt.subplots(nrows=1, ncols=2)
>
> # plot pseoddata in left panel using pcolormesh
> m0 = setup_map(ax[0])
> cm = m0.pcolormesh(lon, lat, data, latlon=True,
>               vmin=0.0, vmax=100.0, cmap=plt.cm.get_cmap("Blues"))
> plt.colorbar(cm, ax=ax[0])
> ax[0].set_title('pcolormesh')
>
> # plot pseoddata in left panel using pcolor
> m1 = setup_map(ax[1])
> cm = m1.pcolor(lon, lat, data, latlon=True,
>           vmin=0.0, vmax=100.0, cmap=plt.cm.get_cmap("Blues"))
> plt.colorbar(cm, ax=ax[1])
> ax[1].set_title('pcolor')
>
> plt.show()
>
>
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