Cannot subset
from SO: http://stackoverflow.com/q/23301072/564538

I'm trying to print three pandas boxplots next to each other in iPython Notebook.

The dataframes each look basically like this:

``` python
sub    cond   accuracy
s1     A      0.814868
s2     A      0.504574
s3     A      0.438314
s4     A      0.956235
s5     A      0.370771
s1     B      0.228724
s2     B      0.691374
s3     B      0.237314
s4     B      0.32633
s5     B      0.859961 
```

When I plot accuracy without subsetting by condition, this works great:

``` python
fig, axes = plt.subplots(nrows=1, ncols=3)
for i, df in enumerate([df1, df2, df3]):
    df.boxplot('accuracy',ax=axes[i])
```

However, when I try to plot accuracy by condition for each dataframe using instead:

``` python
df.boxplot('accuracy',by='cond',ax=axes[i])
```

only the last plot displays (and not where it should be according to its axes assignment). 

This seems to be an issue ing the `by=X` argument.
