ENH: add KDE plot from #1059

Author: wesm

RELEASE.rst

@@ -53,6 +53,7 @@ pandas 0.8.0
   - Add keys() method to DataFrame
   - Add flexible replace method for replacing potentially values to Series and
     DataFrame (#929, #1241)
+  - Add 'kde' plot kind for Series/DataFrame.plot (#1059)
 
 **Improvements to existing features**
 
@@ -70,6 +71,7 @@ pandas 0.8.0
   - Can pass multiple columns to GroupBy object, e.g. grouped[[col1, col2]] to
     only aggregate a subset of the value columns (#383)
   - Add histogram / kde plot options for scatter_matrix diagonals (#1237)
+  - Add inplace option to DataFrame.drop_duplicates (#805)
 
 **API Changes**
 
@@ -101,6 +103,7 @@ pandas 0.8.0
   - Handle Excel 2003 #N/A as NaN from xlrd (#1213, #1225)
   - Fix timestamp locale-related deserialization issues with HDFStore by moving
     to datetime64 representation (#1081, #809)
+  - Fix DataFrame.duplicated/drop_duplicates NA value handling (#557)
 
 pandas 0.7.3
 ============

pandas/tools/plotting.py

@@ -338,6 +338,38 @@ def _get_xticks(self):
 
         return x
 
+class KdePlot(MPLPlot):
+    def __init__(self, data, **kwargs):
+        MPLPlot.__init__(self, data, **kwargs)
+
+    def _get_plot_function(self):
+        return self.plt.Axes.plot
+
+    def _make_plot(self):
+        plotf = self._get_plot_function()
+        for i, (label, y) in enumerate(self._iter_data()):
+            if self.subplots:
+                ax = self.axes[i]
+                style = 'k'
+            else:
+                style = ''  # empty string ignored
+                ax = self.ax
+            if self.style:
+                style = self.style
+            gkde = stats.gaussian_kde(y)
+            sample_range = max(y) - min(y)
+            ind = np.linspace(min(y) - 0.5 * sample_range,
+                max(y) + 0.5 * sample_range, 1000)
+            ax.set_ylabel("Density")
+            plotf(ax, ind, gkde.evaluate(ind), style, label=label, **self.kwds)
+            ax.grid(self.grid)
+
+    def _post_plot_logic(self):
+        df = self.data
+
+        if self.subplots and self.legend:
+            self.axes[0].legend(loc='best')
+
 class LinePlot(MPLPlot):
 
     def __init__(self, data, **kwargs):
@@ -682,6 +714,8 @@ def plot_series(series, label=None, kind='line', use_index=True, rot=None,
         klass = LinePlot
     elif kind in ('bar', 'barh'):
         klass = BarPlot
+    elif kind == 'kde':
+        klass = KdePlot
 
     if ax is None:
         ax = _gca()