DataFrameGroupBy.boxplot with subplots=False fails when using column param

[tdpetrou]

Code Sample, a copy-pastable example if possible

df = pd.DataFrame({'cat':np.random.choice(list('abcde'), 100), 
                    'v':np.random.rand(100), 
                    'v1':np.random.rand(100)})
df.groupby('cat').boxplot(subplots=False, column='v')

outputs
KeyError: "['v'] not in index"

Problem description

The boxplot works when either subplots=False or column='v' but not when they are both specified.

Expected Output

A single axes plot with each group having its own boxplot. The column 'cat' would label the x-axis.

Output of pd.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.6.1.final.0 python-bits: 64 OS: Darwin OS-release: 15.6.0 machine: x86_64 processor: i386 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8

pandas: 0.20.2
pytest: 3.0.7
pip: 9.0.1
setuptools: 35.0.2
Cython: 0.25.2
numpy: 1.13.0
scipy: 0.19.0
xarray: None
IPython: 6.0.0
sphinx: 1.5.5
patsy: 0.4.1
dateutil: 2.6.0
pytz: 2017.2
blosc: None
bottleneck: 1.2.0
tables: 3.4.2
numexpr: 2.6.2
feather: None
matplotlib: 2.0.2
openpyxl: 2.4.7
xlrd: 1.0.0
xlwt: 1.2.0
xlsxwriter: 0.9.6
lxml: 3.7.3
bs4: 4.6.0
html5lib: 0.999999999
sqlalchemy: 1.1.9
pymysql: None
psycopg2: None
jinja2: 2.9.6
s3fs: None
pandas_gbq: None
pandas_datareader: 0.3.0.post

[adhaamehab]

How could i start working on this issue ?

[arpheno]

Experiencing the same issue on pandas 0.20.3

[fuglede]

I also ran into the issue on 0.20.3. Inspired by your own Stack Overflow post, I ended up going with the hacky solution of first boiling down the data frame to what's necessary, plotting through

df[['cat', 'v']].groupby('cat').boxplot(subplots=False)

[TomAugspurger]

With this diff, the example seems to work

diff --git a/pandas/plotting/_core.py b/pandas/plotting/_core.py
index 0d77b5f41..eead95ad3 100644
--- a/pandas/plotting/_core.py
+++ b/pandas/plotting/_core.py
@@ -2373,6 +2373,8 @@ def boxplot_frame_groupby(grouped, subplots=True, column=None, fontsize=None,
                             right=0.9, wspace=0.2)
     else:
         from pandas.core.reshape.concat import concat
+        from pandas import IndexSlice
+
         keys, frames = zip(*grouped)
         if grouped.axis == 0:
             df = concat(frames, keys=keys, axis=1)
@@ -2381,7 +2383,9 @@ def boxplot_frame_groupby(grouped, subplots=True, column=None, fontsize=None,
                 df = frames[0].join(frames[1::])
             else:
                 df = frames[0]
-        ret = df.boxplot(column=column, fontsize=fontsize, rot=rot,
+        if column:
+            df = df.loc[:, IndexSlice[:, column]]
+        ret = df.boxplot(fontsize=fontsize, rot=rot,
                          grid=grid, ax=ax, figsize=figsize,
                          layout=layout, **kwds)
     return ret

Is anyone able to verify that that's correct, and that that fix doesn't break anything else? @ adhaamehab are you still interested in working on this issue (sorry I didn't see your comment the first time around).

[TomAugspurger]

In particular, I haven't explored how that change interacts with the other options to groupby boxplot. I'm not familiar with that section of the codebase.

[tiffanygwilson]

I am also experiencing this issue in pandas 0.20.3. Is anybody working on it? @TomAugspurger the plot for the fix from 18 Oct 2017 looks good except that I think the x-axis labels should just be (for example) a instead of (a, v) since all labels contain v. The hack mentioned by @fuglede works but now throws numpy FutureWarning: reshape is deprecated and will raise in a subsequent release. Please use .values.reshape(...) instead return getattr(obj, method)(*args, **kwds).

[takekazuomi]

I have same issue in pandas 0.23.4.