Fix stem(use_line_collection)

timhoffm · timhoffm · commit 8bf4e0241a50 · 2019-03-23T14:53:33.000+01:00
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -2779,8 +2779,9 @@ def stem(self, *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
 
         # New behaviour in 3.1 is to use a LineCollection for the stemlines
         if use_line_collection:
-            stemlines = []
             stemlines = [((xi, bottom), (xi, yi)) for xi, yi in zip(x, y)]
+            if linestyle is None:
+                linestyle = 'solid'
             stemlines = mcoll.LineCollection(stemlines, linestyles=linestyle,
                                              colors=linecolor,
                                              label='_nolegend_')
