matplotlib · afvincent · Mar 4, 2017 · Mar 5, 2017 · Mar 5, 2017 · Mar 22, 2017
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -1091,55 +1091,82 @@ def eventplot(self, positions, orientation='horizontal', lineoffsets=1,
                   linelengths=1, linewidths=None, colors=None,
                   linestyles='solid', **kwargs):
         """
-        Plot identical parallel lines at specific positions.
+        Plot identical parallel lines at the given positions.
 
-        Plot parallel lines at the given positions.  positions should be a 1D
-        or 2D array-like object, with each row corresponding to a row or column
-        of lines.
+        *positions* should be a 1D or 2D array-like object, with each row
+        corresponding to a row or column of lines.
 
         This type of plot is commonly used in neuroscience for representing
-        neural events, where it is commonly called a spike raster, dot raster,
+        neural events, where it is usually called a spike raster, dot raster,
         or raster plot.
 
         However, it is useful in any situation where you wish to show the
         timing or position of multiple sets of discrete events, such as the
         arrival times of people to a business on each day of the month or the
         date of hurricanes each year of the last century.
 
-        *orientation* : [ 'horizontal' | 'vertical' ]
-          'horizontal' : the lines will be vertical and arranged in rows
-          'vertical' : lines will be horizontal and arranged in columns
+        Parameters
+        ----------
+        positions : 1D or 2D array-like object
+            Each value is an event. If *positions* is a 2D array-like, each
+            row corresponds to a row or a column of lines (depending on the
+            *orientation* parameter).
 
-        *lineoffsets* :
-          A float or array-like containing floats.
+        orientation : {'horizontal', 'vertical'}, optional
+            Controls the direction of the event collections:
 
-        *linelengths* :
-          A float or array-like containing floats.
+                - 'horizontal' : the lines are arranged horizontally in rows,
+                  and are vertical.
+                - 'vertical' : the lines are arranged vertically in columns,
+                  and are horizontal.
 
-        *linewidths* :
-          A float or array-like containing floats.
+        lineoffsets : scalar or sequence of scalars, optional, default: 1
+            The offset of the center of the lines from the origin, in the
+            direction orthogonal to *orientation*.
 
-        *colors*
-          must be a sequence of RGBA tuples (e.g., arbitrary color
-          strings, etc, not allowed) or a list of such sequences
+        linelengths : scalar or sequence of scalars, optional, default: 1
+            The total height of the lines (i.e. the lines stretches from
+            ``lineoffset - linelength/2`` to ``lineoffset + linelength/2``).
 
-        *linestyles* :
-          [ 'solid' | 'dashed' | 'dashdot' | 'dotted' ] or an array of these
-          values
+        linewidths : scalar, scalar sequence or None, optional, default: None
+            The line width(s) of the event lines, in points. If it is None,
+            defaults to its rcParams setting.
 
-        For linelengths, linewidths, colors, and linestyles, if only a single
-        value is given, that value is applied to all lines.  If an array-like
-        is given, it must have the same length as positions, and each value
-        will be applied to the corresponding row or column in positions.
+        colors : color, sequence of colors or None, optional, default: None
+            The color(s) of the event lines. If it is None, defaults to its
+            rcParams setting.
 
-        Returns a list of :class:`matplotlib.collections.EventCollection`
-        objects that were added.
+        linestyles : str or tuple or a sequence of such values, optional
+            Default is 'solid'. Valid strings are ['solid', 'dashed',
+            'dashdot', 'dotted', '-', '--', '-.', ':']. Dash tuples
+            should be of the form::
 
-        kwargs are :class:`~matplotlib.collections.LineCollection` properties:
+                (offset, onoffseq),
 
-        %(LineCollection)s
+            where *onoffseq* is an even length tuple of on and off ink
+            in points.
 
-        **Example:**
+        **kwargs : optional
+            Other keyword arguments are line collection properties.  See
+            :class:`~matplotlib.collections.LineCollection` for a list of
+            the valid properties.
+
+        Returns
+        -------
+
+        A list of :class:`matplotlib.collections.EventCollection` objects that
+        were added.
+
+        Notes
+        -----
+
+        For *linelengths*, *linewidths*, *colors*, and *linestyles*, if only
+        a single value is given, that value is applied to all lines.  If an
+        array-like is given, it must have the same length as *positions*, and
+        each value will be applied to the corresponding row of the array.
+
+        Example
+        -------
 
         .. plot:: mpl_examples/pylab_examples/eventplot_demo.py
         """
@@ -1193,6 +1220,15 @@ def eventplot(self, positions, orientation='horizontal', lineoffsets=1,
             lineoffsets = [None]
         if len(colors) == 0:
             colors = [None]
+        try:
+            # Early conversion of the colors into RGBA values to take care
+            # of cases like colors='0.5' or colors='C1'.  (Issue #8193)
+            colors = mcolors.to_rgba_array(colors)
+        except ValueError:
+            # Will fail if any element of *colors* is None. But as long
+            # as len(colors) == 1 or len(positions), the rest of the
+            # code should process *colors* properly.
+            pass
 
         if len(lineoffsets) == 1 and len(positions) != 1:
             lineoffsets = np.tile(lineoffsets, len(positions))

diff --git a/lib/matplotlib/collections.py b/lib/matplotlib/collections.py
@@ -1243,15 +1243,15 @@ class EventCollection(LineCollection):
     '''
     A collection of discrete events.
 
-    An event is a 1-dimensional value, usually the position of something along
-    an axis, such as time or length.  Events do not have an amplitude.  They
-    are displayed as v
+    The events are given by a 1-dimensional array, usually the position of
+    something along an axis, such as time or length.  They do not have an
+    amplitude and are displayed as vertical or horizontal parallel bars.
     '''
 
     _edge_default = True
 
     def __init__(self,
-                 positions,     # Can be None.
+                 positions,     # Cannot be None.
                  orientation=None,
                  lineoffset=0,
                  linelength=1,
@@ -1262,62 +1262,60 @@ def __init__(self,
                  **kwargs
                  ):
         """
-        *positions*
-            a sequence of numerical values or a 1D numpy array.  Can be None
-
-        *orientation* [ 'horizontal' | 'vertical' | None ]
-            defaults to 'horizontal' if not specified or None
+        Parameters
+        ----------
+        positions : 1D array-like object
+            Each value is an event.
 
-        *lineoffset*
-            a single numerical value, corresponding to the offset of the center
-            of the markers from the origin
+        orientation : {None, 'horizontal', 'vertical'}, optional
+            The orientation of the **collection** (the event bars are along
+            the orthogonal direction). Defaults to 'horizontal' if not
+            specified or None.
 
-        *linelength*
-            a single numerical value, corresponding to the total height of the
-            marker (i.e. the marker stretches from lineoffset+linelength/2 to
-            lineoffset-linelength/2).  Defaults to 1
+        lineoffset : scalar, optional, default: 0
+            The offset of the center of the markers from the origin, in the
+            direction orthogonal to *orientation*.
 
-        *linewidth*
-            a single numerical value
+        linelength : scalar, optional, default: 1
+            The total height of the marker (i.e. the marker stretches from
+            ``lineoffset - linelength/2`` to ``lineoffset + linelength/2``).
 
-        *color*
-            must be a sequence of RGBA tuples (e.g., arbitrary color
-            strings, etc, not allowed).
+        linewidth : scalar or None, optional, default: None
+            If it is None, defaults to its rcParams setting, in sequence form.
 
-        *linestyle* [ 'solid' | 'dashed' | 'dashdot' | 'dotted' ]
+        color : color, sequence of colors or None, optional, default: None
+            If it is None, defaults to its rcParams setting, in sequence form.
 
-        *antialiased*
-            1 or 2
+        linestyle : str or tuple, optional, default: 'solid'
+            Valid strings are ['solid', 'dashed', 'dashdot', 'dotted',
+            '-', '--', '-.', ':']. Dash tuples should be of the form::
 
-        If *linewidth*, *color*, or *antialiased* is None, they
-        default to their rcParams setting, in sequence form.
+                (offset, onoffseq),
 
-        *norm*
-            None (optional for :class:`matplotlib.cm.ScalarMappable`)
-        *cmap*
-            None (optional for :class:`matplotlib.cm.ScalarMappable`)
+            where *onoffseq* is an even length tuple of on and off ink
+            in points.
 
-        *pickradius* is the tolerance for mouse clicks picking a line.
-        The default is 5 pt.
+        antialiased : {None, 1, 2}, optional
+            If it is None, defaults to its rcParams setting, in sequence form.
 
-        The use of :class:`~matplotlib.cm.ScalarMappable` is optional.
-        If the :class:`~matplotlib.cm.ScalarMappable` array
-        :attr:`~matplotlib.cm.ScalarMappable._A` is not None (i.e., a call to
-        :meth:`~matplotlib.cm.ScalarMappable.set_array` has been made), at
-        draw time a call to scalar mappable will be made to set the colors.
+        **kwargs : optional
+            Other keyword arguments are line collection properties.  See
+            :class:`~matplotlib.collections.LineCollection` for a list of
+            the valid properties.
 
-        **Example:**
+        Example
+        -------
 
         .. plot:: mpl_examples/pylab_examples/eventcollection_demo.py
         """
 
         segment = (lineoffset + linelength / 2.,
                    lineoffset - linelength / 2.)
-        if len(positions) == 0:
+        if positions is None or len(positions) == 0:
             segments = []
         elif hasattr(positions, 'ndim') and positions.ndim > 1:
-            raise ValueError('if positions is an ndarry it cannot have '
-                             'dimensionality great than 1 ')
+            raise ValueError('positions cannot be an array with more than '
+                             'one dimension.')
         elif (orientation is None or orientation.lower() == 'none' or
               orientation.lower() == 'horizontal'):
             positions.sort()

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -27,6 +27,7 @@
 import matplotlib.colors as mcolors
 from numpy.testing import assert_allclose, assert_array_equal
 from matplotlib.cbook import IgnoredKeywordWarning
+from matplotlib.cbook._backports import broadcast_to
 
 # Note: Some test cases are run twice: once normally and once with labeled data
 #       These two must be defined in the same test function or need to have
@@ -2909,6 +2910,34 @@ def test_eventplot_defaults():
     colls = axobj.eventplot(data)
 
 
+@pytest.mark.parametrize(('colors'), [
+    ('0.5',),  # string color with multiple characters: not OK before #8193 fix
+    ('tab:orange', 'tab:pink', 'tab:cyan', 'bLacK'),  # case-insensitive
+    ('red', (0, 1, 0), None, (1, 0, 1, 0.5)),  # a tricky case mixing types
+    ('rgbk',)  # len('rgbk') == len(data) and each character is a valid color
+])
+def test_eventplot_colors(colors):
+    '''Test the *colors* parameter of eventplot. Inspired by the issue #8193.
+    '''
+    data = [[i] for i in range(4)]  # 4 successive events of different nature
+
+    # Build the list of the expected colors
+    expected = [c if c is not None else 'C0' for c in colors]
+    # Convert the list into an array of RGBA values
+    # NB: ['rgbk'] is not a valid argument for to_rgba_array, while 'rgbk' is.
+    if len(expected) == 1:
+        expected = expected[0]
+    expected = broadcast_to(mcolors.to_rgba_array(expected), (len(data), 4))
+
+    fig, ax = plt.subplots()
+    if len(colors) == 1:  # tuple with a single string (like '0.5' or 'rgbk')
+        colors = colors[0]
+    collections = ax.eventplot(data, colors=colors)
+
+    for coll, color in zip(collections, expected):
+        assert_allclose(coll.get_color(), color)
+
+
 @image_comparison(baseline_images=['test_eventplot_problem_kwargs'],
                   extensions=['png'], remove_text=True)
 def test_eventplot_problem_kwargs():