pandas - boxplot median color settings issues

Question

I'm running Pandas 0.16.2 and Matplotlib 1.4.3. I have this issue coloring the median of the boxplot generated by the following code:

df = pd.DataFrame(np.random.rand(10, 5), columns=['A', 'B', 'C', 'D', 'E'])

fig, ax = plt.subplots()

medianprops = dict(linestyle='-', linewidth=2, color='blue')

bp = df.boxplot(medianprops=medianprops)

plt.show()

That returns:

It appears that the color setting is not read. Changing only the settings of linestyle and linewidth the plot reacts correctly.

medianprops = dict(linestyle='-.', linewidth=5, color='blue')

Anyone can reproduce it?

score 8 · Answer 1 · answered Sep 10 '15 at 14:13

8

Looking at the code for DataFrame.boxplot() there is some special code to handle the colors of the different elements that supersedes the kws passed to matplotlib's boxplot. In theory, there seem to be a way to pass a color= argument containing a dictionary with keys being 'boxes', 'whiskers', 'medians', 'caps' but I can't seem to get it to work when calling boxplot() directly.

However, this seem to work:

df.plot(kind='box', color={'medians': 'blue'}, 
        medianprops={'linestyle': '--', 'linewidth': 5})

see Pandas Boxplot Examples

answered Sep 10 '15 at 14:13

Diziet Asahi

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1

Thanks, but for my purposes in plotting a multindexed dataframe I need the boxplot function (with 'by' column) instead of the kind='box' version. – Fabio Lamanna Sep 10 '15 at 14:17
Actually using [this](http://stackoverflow.com/a/28103385/2699288) answer it works! – Fabio Lamanna Sep 10 '15 at 14:35

score 1 · Accepted Answer · answered Sep 24 '15 at 14:19

Actually the following workaround works well, returning a dict from the boxplot command:

df = pd.DataFrame(np.random.rand(10, 5), columns=['A', 'B', 'C', 'D', 'E'])

fig, ax = plt.subplots()

bp = df.boxplot(return_type='dict')

and then assign directly colors and linewidth to the medians with:

[[item.set_color('r') for item in bp[key]['medians']] for key in bp.keys()]
[[item.set_linewidth(0.8) for item in bp[key]['medians']] for key in bp.keys()]

pandas - boxplot median color settings issues

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