From 7b2827b3c149df4df09a4fef61afdc75109fbc38 Mon Sep 17 00:00:00 2001
From: Wouter Overmeire <lodagro@gmail.com>
Date: Fri, 18 Nov 2011 09:52:15 +0100
Subject: [PATCH 1/2] DataFrame.boxplot() now returns
 matplotlib.axes.AxesSubplot

---
 pandas/core/frame.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 0e22965d13e21..8bb11104e35ef 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -3054,6 +3054,7 @@ def boxplot(self, column=None, by=None, ax=None, fontsize=None,
         ax = plots.boxplot(self, column=column, by=by, ax=ax, fontsize=fontsize,
                            grid=grid, rot=rot)
         plt.draw_if_interactive()
+        return ax
 
     def plot(self, subplots=False, sharex=True, sharey=False, use_index=True,
              figsize=None, grid=True, legend=True, rot=30, ax=None,

From cdc16529ed858477e226941cb5faa14e80be887e Mon Sep 17 00:00:00 2001
From: Wouter Overmeire <lodagro@gmail.com>
Date: Fri, 18 Nov 2011 09:53:44 +0100
Subject: [PATCH 2/2] Handle boxplot arguments column and grid properly.

---
 pandas/tools/plotting.py | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/pandas/tools/plotting.py b/pandas/tools/plotting.py
index 00eb9ee51f2d0..7f2586e4f76ae 100644
--- a/pandas/tools/plotting.py
+++ b/pandas/tools/plotting.py
@@ -21,7 +21,7 @@ def boxplot(data, column=None, by=None, ax=None, fontsize=None,
     Parameters
     ----------
     data : DataFrame
-    column : column names or list of names, or vector
+    column : column name or list of names, or vector
         Can be any valid input to groupby
     by : string or sequence
         Column in the DataFrame to group by
@@ -37,22 +37,34 @@ def plot_group(grouped, ax):
         ax.boxplot(values)
         ax.set_xticklabels(keys, rotation=rot, fontsize=fontsize)
 
+    if column == None:
+        columns = None
+    else:
+        if isinstance(column, (list, tuple)):
+            columns = column
+        else:
+            columns = [column]
+
     if by is not None:
         if not isinstance(by, (list, tuple)):
             by = [by]
 
-        columns = None if column is None else [column]
         fig, axes = _grouped_plot_by_column(plot_group, data, columns=columns,
-                                            by=by)
+                                            by=by, grid=grid)
         ax = axes
     else:
         if ax is None:
             ax = plt.gca()
 
         data = data._get_numeric_data()
-        keys = [_stringify(x) for x in data.columns]
-        ax.boxplot(list(data.values.T))
+        if columns:
+            cols = columns
+        else:
+            cols = data.columns
+        keys = [_stringify(x) for x in cols]
+        ax.boxplot(list(data[cols].values.T))
         ax.set_xticklabels(keys, rotation=rot, fontsize=fontsize)
+        ax.grid(grid)
 
     plt.subplots_adjust(bottom=0.15, top=0.9, left=0.1, right=0.9, wspace=0.1)
     return ax
@@ -108,7 +120,7 @@ def _grouped_plot(plotf, data, by=None, numeric_only=True):
     return fig, axes
 
 def _grouped_plot_by_column(plotf, data, columns=None, by=None,
-                            numeric_only=True):
+                            numeric_only=True, grid=False):
     grouped = data.groupby(by)
     if columns is None:
         columns = data._get_numeric_data().columns - by
@@ -123,13 +135,17 @@ def _grouped_plot_by_column(plotf, data, columns=None, by=None,
     else:
         ravel_axes = []
         for row in axes:
-            ravel_axes.extend(row)
+            if isinstance(row, plt.Axes):
+                ravel_axes.append(row)
+            else:
+                ravel_axes.extend(row)
 
     for i, col in enumerate(columns):
         ax = ravel_axes[i]
         gp_col = grouped[col]
         plotf(gp_col, ax)
         ax.set_title(col)
+        ax.grid(grid)
 
     fig.suptitle('Boxplot grouped by %s' % by)