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BUG: colorbar autoscaling now ensures a finite range of values #2858

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Merged
merged 1 commit into from
Mar 3, 2014
Merged

BUG: colorbar autoscaling now ensures a finite range of values #2858

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16 changes: 8 additions & 8 deletions lib/matplotlib/colorbar.py
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Original file line number Diff line number Diff line change
Expand Up @@ -551,8 +551,8 @@ def add_lines(self, levels, colors, linewidths, erase=True):

def _ticker(self):
'''
Return two sequences: ticks (colorbar data locations)
and ticklabels (strings).
Return the sequence of ticks (colorbar data locations),
ticklabels (strings), and the corresponding offset string.
'''
locator = self.locator
formatter = self.formatter
Expand Down Expand Up @@ -653,6 +653,9 @@ def _process_values(self, b=None):
self._values = v
return
else:
self.norm.vmin, self.norm.vmax = mtrans.nonsingular(self.norm.vmin,
self.norm.vmax,
expander=0.1)
if not self.norm.scaled():
self.norm.vmin = 0
self.norm.vmax = 1
Expand Down Expand Up @@ -817,24 +820,21 @@ def _locate(self, x):
# as to make the interpolation more accurate.
b = self.norm(self._boundaries, clip=False).filled()
xn = self.norm(x, clip=False).filled()

# The rest is linear interpolation with extrapolation at ends.
y = self._y
N = len(b)
ii = np.searchsorted(b, xn)
i0 = ii - 1
itop = (ii == N)
itop = (ii == len(b))
ibot = (ii == 0)
i0[itop] -= 1
ii[itop] -= 1
i0[ibot] += 1
ii[ibot] += 1

#db = b[ii] - b[i0]
db = np.take(b, ii) - np.take(b, i0)
#dy = y[ii] - y[i0]
y = self._y
dy = np.take(y, ii) - np.take(y, i0)
z = np.take(y, i0) + (xn - np.take(b, i0)) * dy / db

return z

def set_alpha(self, alpha):
Expand Down
Binary file added lib/matplotlib/tests/baseline_images/test_colorbar/colorbar_single_scatter.png
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16 changes: 16 additions & 0 deletions lib/matplotlib/tests/test_colorbar.py
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Expand Up @@ -195,6 +195,22 @@ def test_gridspec_make_colorbar():
plt.subplots_adjust(top=0.95, right=0.95, bottom=0.2, hspace=0.25)

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missing line here (and maybe under it too).


@image_comparison(baseline_images=['colorbar_single_scatter'],
extensions=['png'], remove_text=True,
savefig_kwarg={'dpi': 40})
def test_colorbar_single_scatter():
# Issue #2642: if a path collection has only one entry,
# the norm scaling within the colorbar must ensure a
# finite range, otherwise a zero denominator will occur in _locate.
plt.figure()
x = np.arange(4)
y = x.copy()
z = np.ma.masked_greater(np.arange(50, 54), 50)
cmap = plt.get_cmap('jet', 16)
cs = plt.scatter(x, y, z, c=z, cmap=cmap)
plt.colorbar(cs)


if __name__ == '__main__':
import nose
nose.runmodule(argv=['-s', '--with-doctest'], exit=False)