Add startangle as argument to pie charts

ezratest · ezratest · commit 7fb1c98f268a · 2012-05-04T22:05:52.000-04:00
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,3 +1,7 @@
+2012-05-04 Add a new argument to pie charts - startingangle - that
+	   allows one to specify the angle offset to the first wedge
+	   of the chart. - EP
+
 2012-04-06 When path clipping changes a LINETO to a MOVETO, it also
            changes any CLOSEPOLY command to a LINETO to the initial
            point. This fixes a problem with pdf and svg where the
diff --git a/lib/matplotlib/axes.py b/lib/matplotlib/axes.py
@@ -5005,13 +5005,14 @@ def stem(self, x, y, linefmt='b-', markerfmt='bo', basefmt='r-',
 
     def pie(self, x, explode=None, labels=None, colors=None,
             autopct=None, pctdistance=0.6, shadow=False,
-            labeldistance=1.1):
+            labeldistance=1.1, startangle=None):
         r"""
         Call signature::
 
           pie(x, explode=None, labels=None,
               colors=('b', 'g', 'r', 'c', 'm', 'y', 'k', 'w'),
-              autopct=None, pctdistance=0.6, labeldistance=1.1, shadow=False)
+              autopct=None, pctdistance=0.6, labeldistance=1.1,
+              shadow=False, startangle=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
@@ -5048,6 +5049,10 @@ def pie(self, x, explode=None, labels=None, colors=None,
           *shadow*: [ *False* | *True* ]
             Draw a shadow beneath the pie.
 
+          *startangle*: [ *None* | Offset angle ]
+            If not *None*, rotates the start of the pie chart by *angle*
+            degrees.
+
         The pie chart will probably look best if the figure and axes are
         square.  Eg.::
 
@@ -5085,8 +5090,14 @@ def pie(self, x, explode=None, labels=None, colors=None,
 
         center = 0,0
         radius = 1
-        theta1 = 0
         i = 0
+
+        # Starting theta1 is the start fraction of the circle
+        if startangle is None:
+            theta1 = 0
+        else:
+            theta1 = startangle / 360.0
+            
         texts = []
         slices = []
         autotexts = []
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -2442,15 +2442,15 @@ def pcolormesh(*args, **kwargs):
 # This function was autogenerated by boilerplate.py.  Do not edit as
 # changes will be lost
 @autogen_docstring(Axes.pie)
-def pie(x, explode=None, labels=None, colors=None, autopct=None, pctdistance=0.59999999999999998, shadow=False, labeldistance=1.1000000000000001, hold=None):
+def pie(x, explode=None, labels=None, colors=None, autopct=None, pctdistance=0.6, shadow=False, labeldistance=1.1, startangle=None, hold=None):
     ax = gca()
     # allow callers to override the hold state by passing hold=True|False
     washold = ax.ishold()
 
     if hold is not None:
         ax.hold(hold)
     try:
-        ret = ax.pie(x, explode, labels, colors, autopct, pctdistance, shadow, labeldistance)
+        ret = ax.pie(x, explode, labels, colors, autopct, pctdistance, shadow, labeldistance, startangle)
         draw_if_interactive()
     finally:
         ax.hold(washold)
