Re: [matplotlib-devel] colorbar patch

[John H. <jdh...@ac...>]

>>>>> "Jeff" == Jeff Whitaker <js...@fa...> writes:

    Jeff> Here's a patch against 0.83.2 that modifies colorbar to use
    Jeff> contourf instead of imshow (so that only those colors used
    Jeff> by contourf are shown on the colorbar).  It also adds a few
    Jeff> keyword options to colorbar to 1) allow for linear spacing
    Jeff> of colors on the colorbar (even if the contour levels are
    Jeff> not linear), and 2) draw lines on the colorbar between the
    Jeff> individual colors. Eric and Jim: I think you have both been
    Jeff> hacking on colorbar, perhaps we could merge your changes
    Jeff> into this patch?  Otherwise, if no one has any objections,
    Jeff> I'll commit this to CVS later this week.

I haven't tested this but I did read over it and have one minor
comment

I tend to avoid catching all exceptions as in

+        try:
+        # mappable image is from contourf
+            clevs = array(mappable.levels.tolist() + [mappable.level_upper])
+            iscontourf = True
+        except:
+        # from imshow or pcolor.
+            iscontourf = False
+            norm = mappable.norm
+            if norm.vmin is None or norm.vmax is None:
+                mappable.autoscale()
+            cmin = norm.vmin
+            cmax = norm.vmax
+            clevs = linspace(cmin, cmax, cmap.N)

because they can lead to hard to track bugs.  I suggest either
catching an AttributeError or testing explicitly for ContourMappable,
eg

if isinstance(mappable, ContourMappable):
   # do something
elif isinstance(mappable, ScalarMappable):
   # do something else
else:
   Raise TypeError("don't know how to handle type %s"%type(mappable))

Thanks,
JDH