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BUG: when autoscaling, handle tiny but non-zero values; closes #4318 #4717

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Merged
merged 1 commit into from
Jul 17, 2015
Merged

BUG: when autoscaling, handle tiny but non-zero values; closes #4318 #4717

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9 changes: 9 additions & 0 deletions lib/matplotlib/tests/test_transforms.py
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Original file line number Diff line number Diff line change
Expand Up @@ -552,6 +552,15 @@ def test_transform_angles():
assert_raises(ValueError, t.transform_angles, angles, points[0:2, :])


def test_nonsingular():
# test for zero-expansion type cases; other cases may be added later
zero_expansion = np.array([-0.001, 0.001])
cases = [(0, np.nan), (0, 0), (0, 7.9e-317)]
for args in cases:
out = np.array(mtrans.nonsingular(*args))
assert_array_equal(out, zero_expansion)


if __name__ == '__main__':
import nose
nose.runmodule(argv=['-s', '--with-doctest'], exit=False)
13 changes: 10 additions & 3 deletions lib/matplotlib/transforms.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2726,16 +2726,23 @@ def nonsingular(vmin, vmax, expander=0.001, tiny=1e-15, increasing=True):

Returns *vmin*, *vmax*, expanded and/or swapped if necessary.

If either input is inf or NaN, or if both inputs are 0,
returns -*expander*, *expander*.
If either input is inf or NaN, or if both inputs are 0 or very
close to zero, it returns -*expander*, *expander*.
'''
if (not np.isfinite(vmin)) or (not np.isfinite(vmax)):
return -expander, expander

swapped = False
if vmax < vmin:
vmin, vmax = vmax, vmin
swapped = True
if vmax - vmin <= max(abs(vmin), abs(vmax)) * tiny:

maxabsvalue = max(abs(vmin), abs(vmax))
if maxabsvalue < (1e6 / tiny) * np.MachAr(float).xmin:
vmin = -expander
vmax = expander

elif vmax - vmin <= maxabsvalue * tiny:
if vmax == 0 and vmin == 0:
vmin = -expander
vmax = expander
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