On 7/14/10 11:27 AM, David Sanders wrote:
I have been playing with this a bit, and have found some problems.
Firstly, with this code it seems not to be possible to make a
region_plot *without* specifying opacity -- it looks like a default
argument is missing somewhere.
I've noted this on the trac ticket; thanks.
But the main problem is the same one as I started with. Currently,
each region_plot paints the part which is not "inside" the region in
white (by default), as opposed to leaving it "blank". This means that
when opacity != 0.5, the second plot drawn still partially hides the
first.
Ah, so outcol should by default be set to a 100% transparent color?
I'm having difficulty getting matplotlib to draw a contour plot with a
color map where one of the colors is transparent.
My preferred behaviour would be simply to not draw anything if, for
example, outcol == None.
Perhaps this is not the right place for this discussion (is that the
sage-devel list?), but I tried to modify the code to do this, by
checking for outcol as follows:
if outcol:
g.add_primitive(ContourPlot(xy_data_array, xrange,yrange,
dict(contours=[-1e307, 0, 1e307],
cmap=cmap, fill=True, **options)))
else:
g.add_primitive(ContourPlot(xy_data_array, xrange,yrange,
dict(contours=[-1e307, 0], cmap=cmap,
fill=True, **options)))
(I also checked for it where it is converted to an rgbcolor.)
So if outcol==None, then it should only fill the negative region,
which corresponds to where the arguments are true.
However, I never got this to work, apparently because I don't
understand properly what the cmap object does and how it works.
Directly in matplotlib I did manage to do what I wanted, but not
specifying a cmap. Here I can't seem to get it quite right, but it
seems to me like this is the right direction to go in.
Can somebody enlighten me on cmap?
(yes, I know this is an old thread---I'm catching up...)
How did you get it to work in matplotlib?
The documentation for matplotlib cmaps (i.e., "color maps"---classes
that convert a scalar to an rgba color with transparency) is here:
http://matplotlib.sourceforge.net/api/cm_api.html
See also:
http://matplotlib.sourceforge.net/api/colors_api.html#matplotlib.colors.Colormap
http://matplotlib.sourceforge.net/api/colors_api.html#matplotlib.colors.LinearSegmentedColormap
http://matplotlib.sourceforge.net/api/colors_api.html#matplotlib.colors.ListedColormap
Thanks,
Jason
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