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Backport PR #14040 on branch v3.1.x (Gracefully handle non-finite z in tricontour (issue #10167)) #14522

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Merged
merged 1 commit into from
Jun 10, 2019
Merged

Backport PR #14040 on branch v3.1.x (Gracefully handle non-finite z in tricontour (issue #10167)) #14522

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24 changes: 24 additions & 0 deletions lib/matplotlib/tests/test_triangulation.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1122,3 +1122,27 @@ def test_qhull_large_offset():
triang = mtri.Triangulation(x, y)
triang_offset = mtri.Triangulation(x + offset, y + offset)
assert len(triang.triangles) == len(triang_offset.triangles)


def test_tricontour_non_finite_z():
# github issue 10167.
x = [0, 1, 0, 1]
y = [0, 0, 1, 1]
triang = mtri.Triangulation(x, y)
plt.figure()

with pytest.raises(ValueError, match='z array must not contain non-finite '
'values within the triangulation'):
plt.tricontourf(triang, [0, 1, 2, np.inf])

with pytest.raises(ValueError, match='z array must not contain non-finite '
'values within the triangulation'):
plt.tricontourf(triang, [0, 1, 2, -np.inf])

with pytest.raises(ValueError, match='z array must not contain non-finite '
'values within the triangulation'):
plt.tricontourf(triang, [0, 1, 2, np.nan])

with pytest.raises(ValueError, match='z must not contain masked points '
'within the triangulation'):
plt.tricontourf(triang, np.ma.array([0, 1, 2, 3], mask=[1, 0, 0, 0]))
18 changes: 15 additions & 3 deletions lib/matplotlib/tri/tricontour.py
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Expand Up @@ -79,12 +79,24 @@ def _contour_args(self, args, kwargs):
fn = 'contour'
tri, args, kwargs = Triangulation.get_from_args_and_kwargs(*args,
**kwargs)
z = np.asarray(args[0])
z = np.ma.asarray(args[0])
if z.shape != tri.x.shape:
raise ValueError('z array must have same length as triangulation x'
' and y arrays')
self.zmax = z.max()
self.zmin = z.min()

# z values must be finite, only need to check points that are included
# in the triangulation.
z_check = z[np.unique(tri.get_masked_triangles())]
if np.ma.is_masked(z_check):
raise ValueError('z must not contain masked points within the '
'triangulation')
if not np.isfinite(z_check).all():
raise ValueError('z array must not contain non-finite values '
'within the triangulation')

z = np.ma.masked_invalid(z, copy=False)
self.zmax = float(z_check.max())
self.zmin = float(z_check.min())
if self.logscale and self.zmin <= 0:
raise ValueError('Cannot %s log of negative values.' % fn)
self._contour_level_args(z, args[1:])
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