@@ -117,9 +117,6 @@ def __call__(self, ax, renderer):
117117self ._transform - ax .figure .transSubfigure )
118118
119119
120- _FORMAT_UNSET = 'None'
121-
122-
123120def _process_plot_format (fmt ):
124121"""
125122 Convert a MATLAB style color/line style format string to a (*linestyle*,
@@ -134,7 +131,7 @@ def _process_plot_format(fmt):
134131
135132 The format is absolute in the sense that if a linestyle or marker is not
136133 defined in *fmt*, there is no line or marker. This is expressed by
137- returning_FORMAT_UNSET for the respective quantity.
134+ returning'none' for the respective quantity.
138135
139136 See Also
140137 --------
@@ -203,9 +200,9 @@ def _process_plot_format(fmt):
203200if linestyle is None and marker is None :
204201linestyle = mpl .rcParams ['lines.linestyle' ]
205202if linestyle is None :
206- linestyle = _FORMAT_UNSET
203+ linestyle = 'none'
207204if marker is None :
208- marker = _FORMAT_UNSET
205+ marker = 'none'
209206
210207return linestyle ,marker ,color
211208
@@ -471,13 +468,17 @@ def _plot_args(self, tup, kwargs, return_kwargs=False):
471468# check for conflicts between fmt and kwargs
472469if (fmt .lower ()!= 'none'
473470and prop_name in kwargs
474- and val != _FORMAT_UNSET ):
471+ and val != 'none' ):
475472# Technically ``plot(x, y, 'o', ls='--')`` is a conflict
476473# because 'o' implicitly unsets the linestyle
477- # (linestyle=_FORMAT_UNSET ).
474+ # (linestyle='none' ).
478475# We'll gracefully not warn in this case because an
479476# explicit set via kwargs can be seen as intention to
480477# override an implicit unset.
478+ # Note: We don't val.lower() != 'none' because val is not
479+ # necessarily a string (can be a tuple for colors). This
480+ # is safe, because *val* comes from _process_plot_format()
481+ # which only returns lowercase 'none'.
481482_api .warn_external (
482483f"{ prop_name }
483484f"'{ prop_name }