import collections.abc

import itertools

import numpy as np

import matplotlib.cbook as cbook

import matplotlib.colors as mcolors

import matplotlib.lines as mlines

def check_non_empty(key, value):

"""Raise a TypeError if an empty sequence is passed"""

if (not cbook.is_scalar_or_string(value) and

isinstance(value, collections.abc.Sized) and len(value) == 0):

raise TypeError(f'{key} must not be an empty sequence')

def style_generator(kw):

"""

Helper for handling style sequences (e.g. facecolor=['r', 'b', 'k']) within plotting

methods that repeatedly call other plotting methods (e.g. hist, stackplot). Remove

style keywords from the given dictionary. Return the reduced dictionary together

with a generator which provides a series of dictionaries to be used in each call to

the wrapped function.

"""

kw_iterators = {}

remaining_kw = {}

for key, value in kw.items():

if key in ['facecolor', 'edgecolor']:

if value is None or cbook._str_lower_equal(value, 'none'):

kw_iterators[key] = itertools.repeat(value)

else:

check_non_empty(key, value)

kw_iterators[key] = itertools.cycle(mcolors.to_rgba_array(value))

elif key in ['hatch', 'linewidth']:

check_non_empty(key, value)

kw_iterators[key] = itertools.cycle(np.atleast_1d(value))

elif key == 'linestyle':

check_non_empty(key, value)

kw_iterators[key] = itertools.cycle(mlines._get_dash_patterns(value))

else:

remaining_kw[key] = value

def style_gen():

while True:

yield {key: next(val) for key, val in kw_iterators.items()}

return remaining_kw, style_gen()