matplotlib
diff --git a/‎doc/users/next_whats_new/stripey_lines.rst
Lines changed: 19 additions & 0 deletions b/‎doc/users/next_whats_new/stripey_lines.rst
Lines changed: 19 additions & 0 deletions
diff --git a/‎examples/lines_bars_and_markers/line_demo_dash_control.py
Lines changed: 17 additions & 5 deletions b/‎examples/lines_bars_and_markers/line_demo_dash_control.py
Lines changed: 17 additions & 5 deletions
diff --git a/‎lib/matplotlib/lines.py
Lines changed: 38 additions & 3 deletions b/‎lib/matplotlib/lines.py
Lines changed: 38 additions & 3 deletions
diff --git a/‎lib/matplotlib/tests/baseline_images/test_lines/striped_line.png
25.4 KB b/‎lib/matplotlib/tests/baseline_images/test_lines/striped_line.png
25.4 KB
@@ -0,0 +1,19 @@
+Stripey Lines
+-------------
+
+New *offcolor* parameter enables the creation of stripey lines.
+
+.. plot::
+    :include-source: true
+
+    import matplotlib.pyplot as plt
+    import numpy as np
+
+    x = np.linspace(1., 3., 10)
+    y = x**3
+
+    fig, ax = plt.subplots()
+    ax.plot(x, y, linestyle='--', color='orange', offcolor='blue', linewidth=3,
+            label='a striped line')
+    ax.legend()
+    plt.show()
@@ -17,21 +17,33 @@
 :doc:`property_cycle </tutorials/intermediate/color_cycle>`
 by passing a list of dash sequences using the keyword *dashes* to the
 cycler. This is not shown within this example.
+
+Other attributes of the dash may also be set either with the relevant method
+(`~.Line2D.set_dash_capstyle`, `~.Line2D.set_dash_joinstyle`,
+`~.Line2D.set_offcolor`) or by passing the property through a plotting
+function.
 """
 import numpy as np
 import matplotlib.pyplot as plt
 
 x = np.linspace(0, 10, 500)
 y = np.sin(x)
 
+plt.rc('lines', linewidth=2.5)
 fig, ax = plt.subplots()
 
-# Using set_dashes() to modify dashing of an existing line
-line1, = ax.plot(x, y, label='Using set_dashes()')
-line1.set_dashes([2, 2, 10, 2])  # 2pt line, 2pt break, 10pt line, 2pt break
+# Using set_dashes() and set_capstyle() to modify dashing of an existing line.
+line1, = ax.plot(x, y, label='Using set_dashes() and set_dash_capstyle()')
+line1.set_dashes([2, 2, 10, 2])  # 2pt line, 2pt break, 10pt line, 2pt break.
+line1.set_dash_capstyle('round')
 
-# Using plot(..., dashes=...) to set the dashing when creating a line
+# Using plot(..., dashes=...) to set the dashing when creating a line.
 line2, = ax.plot(x, y - 0.2, dashes=[6, 2], label='Using the dashes parameter')
 
-ax.legend()
+# Using plot(..., dashes=..., offcolor=...) to set the dashing and alternating
+# color when creating a line.
+line3, = ax.plot(x, y - 0.4, dashes=[4, 4], offcolor='tab:pink',
+                 label='Using the dashes and offcolor parameters')
+
+ax.legend(handlelength=4)
 plt.show()
@@ -204,6 +204,7 @@ def _slice_or_none(in_v, slc):
 @_api.define_aliases({
     "antialiased": ["aa"],
     "color": ["c"],
+    "offcolor": ["oc"],
     "drawstyle": ["ds"],
     "linestyle": ["ls"],
     "linewidth": ["lw"],
@@ -272,6 +273,7 @@ def __init__(self, xdata, ydata,
                  linewidth=None,  # all Nones default to rc
                  linestyle=None,
                  color=None,
+                 offcolor=None,
                  marker=None,
                  markersize=None,
                  markeredgewidth=None,
@@ -364,6 +366,9 @@ def __init__(self, xdata, ydata,
         else:
             self._marker = marker
 
+        self._offcolor = None
+        self.set_offcolor(offcolor)
+
         self._markevery = None
         self._markersize = None
         self._antialiased = None
@@ -754,9 +759,6 @@ def draw(self, renderer):
                 self._set_gc_clip(gc)
                 gc.set_url(self.get_url())
 
-                lc_rgba = mcolors.to_rgba(self._color, self._alpha)
-                gc.set_foreground(lc_rgba, isRGBA=True)
-
                 gc.set_antialiased(self._antialiased)
                 gc.set_linewidth(self._linewidth)
 
@@ -772,6 +774,16 @@ def draw(self, renderer):
                 if self.get_sketch_params() is not None:
                     gc.set_sketch_params(*self.get_sketch_params())
 
+                # We first draw the path below if needed.
+                if self.is_dashed() and self._offcolor is not None:
+                    lc_rgba = mcolors.to_rgba(self._offcolor, self._alpha)
+                    gc.set_foreground(lc_rgba, isRGBA=True)
+                    gc.set_dashes(0, None)
+                    renderer.draw_path(gc, tpath, affine.frozen())
+
+                lc_rgba = mcolors.to_rgba(self._color, self._alpha)
+                gc.set_foreground(lc_rgba, isRGBA=True)
+
                 gc.set_dashes(*self._dash_pattern)
                 renderer.draw_path(gc, tpath, affine.frozen())
                 gc.restore()
@@ -868,6 +880,14 @@ def get_color(self):
         """
         return self._color
 
+    def get_offcolor(self):
+        """
+        Return the line offcolor.
+
+        See also `~.Line2D.set_offcolor`.
+        """
+        return self._offcolor
+
     def get_drawstyle(self):
         """
         Return the drawstyle.
@@ -1031,6 +1051,20 @@ def set_color(self, color):
         self._color = color
         self.stale = True
 
+    def set_offcolor(self, offcolor):
+        """
+        Set the gap color for the dashed line style.
+
+        Parameters
+        ----------
+        offcolor : color or None
+            The gap color. If None, the gaps are unfilled.
+        """
+        if offcolor is not None:
+            mcolors._check_color_like(color=offcolor)
+        self._offcolor = offcolor
+        self.stale = True
+
     def set_drawstyle(self, drawstyle):
         """
         Set the drawstyle of the plot.
@@ -1264,6 +1298,7 @@ def update_from(self, other):
         self._linestyle = other._linestyle
         self._linewidth = other._linewidth
         self._color = other._color
+        self._offcolor = other._offcolor
         self._markersize = other._markersize
         self._markerfacecolor = other._markerfacecolor
         self._markerfacecoloralt = other._markerfacecoloralt
 
@@ -304,6 +304,16 @@ def test_marker_as_markerstyle():
     assert_array_equal(line3.get_marker().vertices, triangle1.vertices)
 
 
+@image_comparison(['striped_line.png'], remove_text=True, style='mpl20')
+def test_striped_lines():
+    _, ax = plt.subplots()
+    ax.plot([0, 1], color='orange', offcolor='blue', linestyle='--', lw=5,
+            label='standard dash')
+    ax.plot([0, 2], color='red', offcolor='black', linestyle=(0, (2, 5, 4, 2)),
+            lw=5, label='custom dash')
+    ax.legend(handlelength=5)
+
+
 @check_figures_equal()
 def test_odd_dashes(fig_test, fig_ref):
     fig_test.add_subplot().plot([1, 2], dashes=[1, 2, 3])