Add pie startangle kwarg to demo, and add direction info to docstring

efiring · efiring · commit 6a0c44838630 · 2012-05-27T10:52:49.000-10:00
diff --git a/examples/pylab_examples/pie_demo.py b/examples/pylab_examples/pie_demo.py
@@ -3,10 +3,8 @@
 http://matplotlib.sf.net/matplotlib.pylab.html#-pie for the docstring.
 
 This example shows a basic pie chart with labels optional features,
-like autolabeling the percentage, offsetting a slice with "explode"
-and adding a shadow.
-
-Requires matplotlib0-0.70 or later
+like autolabeling the percentage, offsetting a slice with "explode",
+adding a shadow, and changing the starting angle.
 
 """
 from pylab import *
@@ -15,11 +13,18 @@
 figure(1, figsize=(6,6))
 ax = axes([0.1, 0.1, 0.8, 0.8])
 
+# The slices will be ordered and plotted counter-clockwise.
 labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
-fracs = [15,30,45, 10]
-
+fracs = [15, 30, 45, 10]
 explode=(0, 0.05, 0, 0)
-pie(fracs, explode=explode, labels=labels, autopct='%1.1f%%', shadow=True)
+
+pie(fracs, explode=explode, labels=labels,
+                autopct='%1.1f%%', shadow=True, startangle=90)
+                # The default startangle is 0, which would start
+                # the Frogs slice on the x-axis.  With startangle=90,
+                # everything is rotated counter-clockwise by 90 degrees,
+                # so the plotting starts on the positive y-axis.
+
 title('Raining Hogs and Dogs', bbox={'facecolor':'0.8', 'pad':5})
 
 show()
diff --git a/lib/matplotlib/axes.py b/lib/matplotlib/axes.py
@@ -5017,7 +5017,8 @@ def pie(self, x, explode=None, labels=None, colors=None,
         Make a pie chart of array *x*.  The fractional area of each
         wedge is given by x/sum(x).  If sum(x) <= 1, then the values
         of x give the fractional area directly and the array will not
-        be normalized.
+        be normalized.  The wedges are plotted counterclockwise,
+        by default starting from the x-axis.
 
         Keyword arguments:
 
@@ -5051,7 +5052,7 @@ def pie(self, x, explode=None, labels=None, colors=None,
 
           *startangle*: [ *None* | Offset angle ]
             If not *None*, rotates the start of the pie chart by *angle*
-            degrees.
+            degrees counterclockwise from the x-axis.
 
         The pie chart will probably look best if the figure and axes are
         square.  Eg.::
@@ -5097,7 +5098,7 @@ def pie(self, x, explode=None, labels=None, colors=None,
             theta1 = 0
         else:
             theta1 = startangle / 360.0
-            
+
         texts = []
         slices = []
         autotexts = []
@@ -5162,8 +5163,10 @@ def pie(self, x, explode=None, labels=None, colors=None,
         self.set_xticks([])
         self.set_yticks([])
 
-        if autopct is None: return slices, texts
-        else: return slices, texts, autotexts
+        if autopct is None:
+            return slices, texts
+        else:
+            return slices, texts, autotexts
 
     @docstring.dedent_interpd
     def errorbar(self, x, y, yerr=None, xerr=None,
