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Check number of positional arguments passed to quiver() #14084

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Merged
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May 14, 2019
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Check number of positional arguments passed to quiver() #14084

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10 changes: 0 additions & 10 deletions lib/matplotlib/cbook/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2148,16 +2148,6 @@ def _check_and_log_subprocess(command, logger, **kwargs):
return report


def _check_not_matrix(**kwargs):
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@timhoffm timhoffm Apr 29, 2019 •
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This was only used in _parse_args, we don't check anywhere else in the code for np.matrix.

np.matrix itself is not recommended anymore and matplotlib usage: Types of inputs states that np.matrix may or may not work.

Therefore I don't see the need to explicitly check for this to give an error message.

Note also, this currently checked only U, V, C but not X, Y.

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This was added in #13089 to fix #1558 just in 3.1.0; do we really want to revert that check so quickly?

Also, skipping X and Y was done on purpose, though perhaps that's a little unintuitive.

"""
If any value in *kwargs* is a `np.matrix`, raise a TypeError with the key
name in its message.
"""
for k, v in kwargs.items():
if isinstance(v, np.matrix):
raise TypeError(f"Argument {k!r} cannot be a np.matrix")


def _check_in_list(values, **kwargs):
"""
For each *key, value* pair in *kwargs*, check that *value* is in *values*;
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64 changes: 43 additions & 21 deletions lib/matplotlib/quiver.py
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Original file line number Diff line number Diff line change
Expand Up @@ -360,31 +360,53 @@ def quiverkey_doc(self):
return self.__init__.__doc__


# This is a helper function that parses out the various combination of
# arguments for doing colored vector plots. Pulling it out here
# allows both Quiver and Barbs to use it
def _parse_args(*args):
X = Y = U = V = C = None
args = list(args)

# The use of atleast_1d allows for handling scalar arguments while also
# keeping masked arrays
if len(args) == 3 or len(args) == 5:
C = np.atleast_1d(args.pop(-1))
V = np.atleast_1d(args.pop(-1))
U = np.atleast_1d(args.pop(-1))
cbook._check_not_matrix(U=U, V=V, C=C)
if U.ndim == 1:
nr, nc = 1, U.shape[0]
def _parse_args(*args, caller_name='function'):
"""
Helper function to parse positional parameters for colored vector plots.

This is currently used for Quiver and Barbs.

Parameters
----------
*args : list
list of 2-5 arguments. Depending on their number they are parsed to::

U, V
U, V, C
X, Y, U, V
X, Y, U, V, C

caller_name : str
Name of the calling method (used in error messages).
"""
X = Y = C = None

len_args = len(args)
if len_args == 2:
# The use of atleast_1d allows for handling scalar arguments while also
# keeping masked arrays
U, V = np.atleast_1d(*args)
elif len_args == 3:
U, V, C = np.atleast_1d(*args)
elif len_args == 4:
X, Y, U, V = np.atleast_1d(*args)
elif len_args == 5:
X, Y, U, V, C = np.atleast_1d(*args)
else:
nr, nc = U.shape
if len(args) == 2: # remaining after removing U,V,C
X, Y = [np.array(a).ravel() for a in args]
raise TypeError(f'{caller_name} takes 2-5 positional arguments but '
f'{len_args} were given')

nr, nc = (1, U.shape[0]) if U.ndim == 1 else U.shape

if X is not None:
X = X.ravel()
Y = Y.ravel()
if len(X) == nc and len(Y) == nr:
X, Y = [a.ravel() for a in np.meshgrid(X, Y)]
else:
indexgrid = np.meshgrid(np.arange(nc), np.arange(nr))
X, Y = [np.ravel(a) for a in indexgrid]

return X, Y, U, V, C


Expand Down Expand Up @@ -426,7 +448,7 @@ def __init__(self, ax, *args,
%s
"""
self.ax = ax
X, Y, U, V, C = _parse_args(*args)
X, Y, U, V, C = _parse_args(*args, caller_name='quiver()')
self.X = X
self.Y = Y
self.XY = np.column_stack((X, Y))
Expand Down Expand Up @@ -941,7 +963,7 @@ def __init__(self, ax, *args,
kw['linewidth'] = 1

# Parse out the data arrays from the various configurations supported
x, y, u, v, c = _parse_args(*args)
x, y, u, v, c = _parse_args(*args, caller_name='barbs()')
self.x = x
self.y = y
xy = np.column_stack((x, y))
Expand Down
10 changes: 10 additions & 0 deletions lib/matplotlib/tests/test_quiver.py
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,16 @@ def test_quiver_key_memory_leak():
assert sys.getrefcount(qk) == 2


def test_quiver_number_of_args():
X = [1, 2]
with pytest.raises(TypeError,
match='takes 2-5 positional arguments but 1 were given'):
plt.quiver(X)
with pytest.raises(TypeError,
match='takes 2-5 positional arguments but 6 were given'):
plt.quiver(X, X, X, X, X, X)


def test_no_warnings():
fig, ax = plt.subplots()

Expand Down