ENH: Scatterplot Method added

doc/source/release.rst

@@ -210,6 +210,7 @@ API Changes
   - Default export for ``to_clipboard`` is now csv with a sep of `\t` for
     compat (:issue:`3368`)
   - ``at`` now will enlarge the object inplace (and return the same) (:issue:`2578`)
+  - new class added to allow scatterplotting using ``df.plot(kind="scatter")``(:issue:`2215`)
 
   - ``HDFStore``
 

pandas/tests/test_graphics.py

@@ -449,7 +449,7 @@ def test_plot_xy(self):
 
         # columns.inferred_type == 'mixed'
         # TODO add MultiIndex test
-
+        
     @slow
     def test_xcompat(self):
         import pandas as pd
@@ -534,6 +534,21 @@ def test_subplots(self):
             [self.assert_(label.get_visible())
              for label in ax.get_yticklabels()]
 
+    @slow
+    def test_plot_scatter(self):
+        from matplotlib.pylab import close
+        df = DataFrame(randn(6, 4),
+                       index=list(string.ascii_letters[:6]),
+                       columns=['x', 'y', 'z', 'four'])
+
+        _check_plot_works(df.plot, x='x', y='y', kind='scatter')
+        _check_plot_works(df.plot, x=1, y=2, kind='scatter')
+
+        with tm.assertRaises(ValueError):
+            df.plot(x='x', kind='scatter')
+        with tm.assertRaises(ValueError):
+            df.plot(y='y', kind='scatter')
+
     @slow
     def test_plot_bar(self):
         from matplotlib.pylab import close

pandas/tools/plotting.py

@@ -322,7 +322,6 @@ def _gcf():
     import matplotlib.pyplot as plt
     return plt.gcf()
 
-
 def _get_marker_compat(marker):
     import matplotlib.lines as mlines
     import matplotlib as mpl
@@ -1201,7 +1200,32 @@ def _post_plot_logic(self):
             for ax in self.axes:
                 ax.legend(loc='best')
 
-
+class ScatterPlot(MPLPlot):
+    def __init__(self, data, x, y, **kwargs):
+        MPLPlot.__init__(self, data, **kwargs)
+        self.kwds.setdefault('c', self.plt.rcParams['patch.facecolor'])
+        if x is None or y is None:
+            raise ValueError( 'scatter requires and x and y column')
+        if com.is_integer(x) and not self.data.columns.holds_integer():
+            x = self.data.columns[x]
+        if com.is_integer(y) and not self.data.columns.holds_integer():
+            y = self.data.columns[y]
+        self.x = x
+        self.y = y
+
+
+    def _make_plot(self):
+        x, y, data = self.x, self.y, self.data
+        ax = self.axes[0]
+        ax.scatter(data[x].values, data[y].values, **self.kwds)
+
+    def _post_plot_logic(self):
+        ax = self.axes[0]
+        x, y = self.x, self.y   
+        ax.set_ylabel(com.pprint_thing(y))
+        ax.set_xlabel(com.pprint_thing(x))
+
+
 class LinePlot(MPLPlot):
 
     def __init__(self, data, **kwargs):
@@ -1562,7 +1586,7 @@ def plot_frame(frame=None, x=None, y=None, subplots=False, sharex=True,
                secondary_y=False, **kwds):
 
     """
-    Make line or bar plot of DataFrame's series with the index on the x-axis
+    Make line, bar, or scatter plots of DataFrame series with the index on the x-axis
     using matplotlib / pylab.
 
     Parameters
@@ -1593,10 +1617,11 @@ def plot_frame(frame=None, x=None, y=None, subplots=False, sharex=True,
     ax : matplotlib axis object, default None
     style : list or dict
         matplotlib line style per column
-    kind : {'line', 'bar', 'barh', 'kde', 'density'}
+    kind : {'line', 'bar', 'barh', 'kde', 'density', 'scatter'}
         bar : vertical bar plot
         barh : horizontal bar plot
         kde/density : Kernel Density Estimation plot
+        scatter: scatter plot
     logx : boolean, default False
         For line plots, use log scaling on x axis
     logy : boolean, default False
@@ -1632,36 +1657,50 @@ def plot_frame(frame=None, x=None, y=None, subplots=False, sharex=True,
         klass = BarPlot
     elif kind == 'kde':
         klass = KdePlot
+    elif kind == 'scatter':
+        klass = ScatterPlot 
     else:
         raise ValueError('Invalid chart type given %s' % kind)
 
-    if x is not None:
-        if com.is_integer(x) and not frame.columns.holds_integer():
-            x = frame.columns[x]
-        frame = frame.set_index(x)
-
-    if y is not None:
-        if com.is_integer(y) and not frame.columns.holds_integer():
-            y = frame.columns[y]
-        label = x if x is not None else frame.index.name
-        label = kwds.pop('label', label)
-        ser = frame[y]
-        ser.index.name = label
-        return plot_series(ser, label=label, kind=kind,
-                           use_index=use_index,
-                           rot=rot, xticks=xticks, yticks=yticks,
-                           xlim=xlim, ylim=ylim, ax=ax, style=style,
-                           grid=grid, logx=logx, logy=logy,
-                           secondary_y=secondary_y, title=title,
-                           figsize=figsize, fontsize=fontsize, **kwds)
-
-    plot_obj = klass(frame, kind=kind, subplots=subplots, rot=rot,
-                     legend=legend, ax=ax, style=style, fontsize=fontsize,
-                     use_index=use_index, sharex=sharex, sharey=sharey,
-                     xticks=xticks, yticks=yticks, xlim=xlim, ylim=ylim,
-                     title=title, grid=grid, figsize=figsize, logx=logx,
-                     logy=logy, sort_columns=sort_columns,
-                     secondary_y=secondary_y, **kwds)
+    if kind == 'scatter':
+        plot_obj = klass(frame,  x=x, y=y, kind=kind, subplots=subplots, 
+                         rot=rot,legend=legend, ax=ax, style=style, 
+                         fontsize=fontsize, use_index=use_index, sharex=sharex,
+                         sharey=sharey, xticks=xticks, yticks=yticks, 
+                         xlim=xlim, ylim=ylim, title=title, grid=grid, 
+                         figsize=figsize, logx=logx, logy=logy, 
+                         sort_columns=sort_columns, secondary_y=secondary_y, 
+                         **kwds)
+    else:
+        if x is not None:
+            if com.is_integer(x) and not frame.columns.holds_integer():
+                x = frame.columns[x]
+            frame = frame.set_index(x)
+
+        if y is not None:
+            if com.is_integer(y) and not frame.columns.holds_integer():
+                y = frame.columns[y]
+            label = x if x is not None else frame.index.name
+            label = kwds.pop('label', label)
+            ser = frame[y]
+            ser.index.name = label
+            return plot_series(ser, label=label, kind=kind,
+                               use_index=use_index,
+                               rot=rot, xticks=xticks, yticks=yticks,
+                               xlim=xlim, ylim=ylim, ax=ax, style=style,
+                               grid=grid, logx=logx, logy=logy,
+                               secondary_y=secondary_y, title=title,
+                               figsize=figsize, fontsize=fontsize, **kwds)
+
+        else:
+            plot_obj = klass(frame, kind=kind, subplots=subplots, rot=rot,
+                             legend=legend, ax=ax, style=style, fontsize=fontsize,
+                             use_index=use_index, sharex=sharex, sharey=sharey,
+                             xticks=xticks, yticks=yticks, xlim=xlim, ylim=ylim,
+                             title=title, grid=grid, figsize=figsize, logx=logx,
+                             logy=logy, sort_columns=sort_columns,
+                             secondary_y=secondary_y, **kwds)
+
     plot_obj.generate()
     plot_obj.draw()
     if subplots: