[Matplotlib-users] figure.colorbar sometimes raises an exception

[Russell E. O. <ro...@uw...>]

We have code that ran fine in 1.1.1 that raises an exception in colorbar 
in 1.2.1 and 1.3.1. I have appended an example; I'm afraid it is rather 
extreme, but we have seen this for arrays that have more than one 
non-masked values as well, even with the values not all being equal.

Should I report this as a bug? Should we guard all our calls to colormap 
with try/except, or perhaps there's a flag we can set that says "do your 
best"? (But I don't see anything like that in the docs).

-- Russell

        cmap = getattr(cm, cmap)
        cmap.set_bad('k', 0.2)
        if cmapOver is not None:
            cmap.set_over(cmapOver, 1.0)
        if cmapUnder is not None:
            cmap.set_under(cmapUnder, 1.0)
        p = PatchCollection(patches, norm=norm, cmap=cmap)
        value_array = numpy.array(values)
        masked_value_array = 
numpyMa.masked_where(numpy.isnan(value_array), value_array)
        p.set_array(masked_value_array)
        cb = self.fig.colorbar(p)

  File 
"/nfs/lsst/home/rowen/code/testing_pipeQA/python/lsst/testing/pipeQA/figu
res/FpaQaFigure.py", line 317, in makeFigure
    cb = self.fig.colorbar(p)
  File 
"/lsst/DC3/stacks/gcc445-RH6/28nov2011/Linux64/external/matplotlib/1.3.1+
1/lib/python/matplotlib-1.3.1-py2.7-linux-x86_64.egg/matplotlib/figure.py
", line 1451, in colorbar
    cb = cbar.colorbar_factory(cax, mappable, **kw)
  File 
"/lsst/DC3/stacks/gcc445-RH6/28nov2011/Linux64/external/matplotlib/1.3.1+
1/lib/python/matplotlib-1.3.1-py2.7-linux-x86_64.egg/matplotlib/colorbar.
py", line 1274, in colorbar_factory
    cb = Colorbar(cax, mappable, **kwargs)
  File 
"/lsst/DC3/stacks/gcc445-RH6/28nov2011/Linux64/external/matplotlib/1.3.1+
1/lib/python/matplotlib-1.3.1-py2.7-linux-x86_64.egg/matplotlib/colorbar.
py", line 877, in __init__
    ColorbarBase.__init__(self, ax, **kw)
  File 
"/lsst/DC3/stacks/gcc445-RH6/28nov2011/Linux64/external/matplotlib/1.3.1+
1/lib/python/matplotlib-1.3.1-py2.7-linux-x86_64.egg/matplotlib/colorbar.
py", line 317, in __init__
    self.draw_all()
  File 
"/lsst/DC3/stacks/gcc445-RH6/28nov2011/Linux64/external/matplotlib/1.3.1+
1/lib/python/matplotlib-1.3.1-py2.7-linux-x86_64.egg/matplotlib/colorbar.
py", line 342, in draw_all
    self._config_axes(X, Y)
  File 
"/lsst/DC3/stacks/gcc445-RH6/28nov2011/Linux64/external/matplotlib/1.3.1+
1/lib/python/matplotlib-1.3.1-py2.7-linux-x86_64.egg/matplotlib/colorbar.
py", line 433, in _config_axes
    self.update_ticks()
  File 
"/lsst/DC3/stacks/gcc445-RH6/28nov2011/Linux64/external/matplotlib/1.3.1+
1/lib/python/matplotlib-1.3.1-py2.7-linux-x86_64.egg/matplotlib/colorbar.
py", line 367, in update_ticks
    ticks, ticklabels, offset_string = self._ticker()
  File 
"/lsst/DC3/stacks/gcc445-RH6/28nov2011/Linux64/external/matplotlib/1.3.1+
1/lib/python/matplotlib-1.3.1-py2.7-linux-x86_64.egg/matplotlib/colorbar.
py", line 580, in _ticker
    ticks = self._locate(b)
  File 
"/lsst/DC3/stacks/gcc445-RH6/28nov2011/Linux64/external/matplotlib/1.3.1+
1/lib/python/matplotlib-1.3.1-py2.7-linux-x86_64.egg/matplotlib/colorbar.
py", line 829, in _locate
    z = np.take(y, i0) + (xn - np.take(b, i0)) * dy / db
FloatingPointError: invalid value encountered in divide

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