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Various small fixes for streamplot(). #21558

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Merged
merged 1 commit into from
Nov 8, 2021
Merged

Various small fixes for streamplot(). #21558

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23 changes: 12 additions & 11 deletions lib/matplotlib/streamplot.py
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Original file line number Diff line number Diff line change
Expand Up @@ -116,8 +116,8 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
if use_multicolor_lines:
if color.shape != grid.shape:
raise ValueError("If 'color' is given, it must match the shape of "
"'Grid(x, y)'")
line_colors = []
"the (x, y) grid")
line_colors = [[]] # Empty entry allows concatenation of zero arrays.
color = np.ma.masked_invalid(color)
else:
line_kw['color'] = color
Expand All @@ -126,7 +126,7 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
if isinstance(linewidth, np.ndarray):
if linewidth.shape != grid.shape:
raise ValueError("If 'linewidth' is given, it must match the "
"shape of 'Grid(x, y)'")
"shape of the (x, y) grid")
line_kw['linewidth'] = []
else:
line_kw['linewidth'] = linewidth
Expand All @@ -137,7 +137,7 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,

# Sanity checks.
if u.shape != grid.shape or v.shape != grid.shape:
raise ValueError("'u' and 'v' must match the shape of 'Grid(x, y)'")
raise ValueError("'u' and 'v' must match the shape of the (x, y) grid")

u = np.ma.masked_invalid(u)
v = np.ma.masked_invalid(v)
Expand Down Expand Up @@ -310,21 +310,22 @@ class Grid:
"""Grid of data."""
def __init__(self, x, y):

if x.ndim == 1:
if np.ndim(x) == 1:
pass
elif x.ndim == 2:
x_row = x[0, :]
elif np.ndim(x) == 2:
x_row = x[0]
if not np.allclose(x_row, x):
raise ValueError("The rows of 'x' must be equal")
x = x_row
else:
raise ValueError("'x' can have at maximum 2 dimensions")

if y.ndim == 1:
if np.ndim(y) == 1:
pass
elif y.ndim == 2:
y_col = y[:, 0]
if not np.allclose(y_col, y.T):
elif np.ndim(y) == 2:
yt = np.transpose(y) # Also works for nested lists.
y_col = yt[0]
if not np.allclose(y_col, yt):
raise ValueError("The columns of 'y' must be equal")
y = y_col
else:
Expand Down
10 changes: 10 additions & 0 deletions lib/matplotlib/tests/test_streamplot.py
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Original file line number Diff line number Diff line change
Expand Up @@ -144,3 +144,13 @@ def test_streamplot_grid():

with pytest.raises(ValueError, match="'y' must be strictly increasing"):
plt.streamplot(x, y, u, v)


def test_streamplot_inputs(): # test no exception occurs.
# fully-masked
plt.streamplot(np.arange(3), np.arange(3),
np.full((3, 3), np.nan), np.full((3, 3), np.nan),
color=np.random.rand(3, 3))
# array-likes
plt.streamplot(range(3), range(3),
np.random.rand(3, 3), np.random.rand(3, 3))