Merge branch 'epeisach-pie_angle'

efiring · efiring · commit b24824df2fc7 · 2012-05-27T10:55:24.000-10:00
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,17 +1,21 @@
 2012-05-22 Collections now have a setting "offset_position" to select whether
-	   the offsets are given in "screen" coordinates (default,
-	   following the old behavior) or "data" coordinates.  This is currently
-	   used internally to improve the performance of hexbin.
+           the offsets are given in "screen" coordinates (default,
+           following the old behavior) or "data" coordinates.  This is currently
+           used internally to improve the performance of hexbin.
 
-	   As a result, the "draw_path_collection" backend methods have grown
-	   a new argument "offset_position". - MGD
+           As a result, the "draw_path_collection" backend methods have grown
+           a new argument "offset_position". - MGD
+
+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
 
 2012-05-03 symlog scale now obeys the logarithmic base.  Previously, it was
-	   completely ignored and always treated as base e. - MGD
+           completely ignored and always treated as base e. - MGD
 
 2012-05-03 Allow linscalex/y keyword to symlog scale that allows the size of
-	   the linear portion relative to the logarithmic portion to be
-	   adjusted. - MGD
+           the linear portion relative to the logarithmic portion to be
+           adjusted. - MGD
 
 2012-04-06 When path clipping changes a LINETO to a MOVETO, it also
            changes any CLOSEPOLY command to a LINETO to the initial
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
@@ -5005,18 +5005,20 @@ 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
         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:
 
@@ -5048,6 +5050,10 @@ 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 counterclockwise from the x-axis.
+
         The pie chart will probably look best if the figure and axes are
         square.  Eg.::
 
@@ -5085,8 +5091,14 @@ 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 = []
@@ -5151,8 +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,
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)
