Cannot update boxplot via axes

[jorisvandenbossche]

When I construct a boxplot with pandas, e.g. like this:

df = pd.DataFrame({'A':[1,3,2,5,4,7,6], 'B':[1,1,1,1,2,2,2]})
fig, ax = plt.subplots()
df.boxplot('A', 'B', ax=ax)

I cannnot change the plot anymore via ax, e.g. ax.set_ylim(0,20) or ax.set_ylabel("Something") has no effect on the figure.

Complete example: http://nbviewer.ipython.org/5868420/bug_pandas-boxplot-set-ylim.ipynb

I tested it on the dev version of pandas (and I know it worked previously, but cannot check which version exactly anymore).

[jorisvandenbossche]

It seems that if you do

ax = df.boxplot('A', 'B', ax=ax)

instead of just

df.boxplot('A', 'B', ax=ax)

that you then can update the figure via ax. So maybe the axes object is changed in the boxplot function?

[fonnesbeck]

The solution suggested by @jorisvandenbossche does not appear to work, at least as of 0.13.0rc1-64-gceec8bf. I get the following:

AttributeError                            Traceback (most recent call last)
<ipython-input-51-f438708091a3> in <module>()
      1 fig, ax = plt.subplots()
      2 ax = df.boxplot(ax=ax, grid=False)
----> 3 ax.set_xlabel('Patient')

AttributeError: 'dict' object has no attribute 'set_xlabel'

[TomAugspurger]

So boxplot() is returning a dict if things are grouped (the column and by arguments), and an axes if there's no grouping? That doesn't seem great.

@fonnesbeck as a bad workaround, you could grab the axes that the parts are drawn on:

In [150]: fig, ax = plt.subplots()

In [151]: ax = df.boxplot(ax=ax, grid=False)

In [152]: ax
Out[152]: 
{'fliers': [<matplotlib.lines.Line2D at 0x10bde7850>,
  <matplotlib.lines.Line2D at 0x10bdea910>,
  <matplotlib.lines.Line2D at 0x10bdf9c90>,
  <matplotlib.lines.Line2D at 0x10bdfdd50>],
 'caps': [<matplotlib.lines.Line2D at 0x10bddedd0>,
  <matplotlib.lines.Line2D at 0x10bdda0d0>,
  <matplotlib.lines.Line2D at 0x10bdefa50>,
  <matplotlib.lines.Line2D at 0x10bdf4610>],
 'whiskers': [<matplotlib.lines.Line2D at 0x10bdde710>,
  <matplotlib.lines.Line2D at 0x10bdc7190>,
  <matplotlib.lines.Line2D at 0x10bdea9d0>,
  <matplotlib.lines.Line2D at 0x10bdef4d0>],
 'medians': [<matplotlib.lines.Line2D at 0x10bde7110>,
  <matplotlib.lines.Line2D at 0x10bdf9410>],
 'boxes': [<matplotlib.lines.Line2D at 0x10bdd7b10>,
  <matplotlib.lines.Line2D at 0x10bdf4b50>]}

In [153]: real_ax = ax['fliers'][0].get_axes()

In [154]: real_ax.set_xlabel("Patient")
Out[154]: <matplotlib.text.Text at 0x10be51710>

[cpcloud]

closing this ... as it works in all examples shown. if i have some time i'll see if i can find what commit fixes this.