Black and white boxplots in Seaborn

Question

I am trying to draw multiple black-and-white boxplots using Python's Seaborn package. By default the plots are using a color palette. I would like to draw them in solid black outline. The best I can come up with is:

# figure styles
sns.set_style('white')
sns.set_context('paper', font_scale=2)
plt.figure(figsize=(3, 5))
sns.set_style('ticks', {'axes.edgecolor': '0',  
                        'xtick.color': '0',
                        'ytick.color': '0'})

ax = sns.boxplot(x="test1", y="test2", data=dataset, color='white', width=.5)
sns.despine(offset=5, trim=True)
sns.plt.show()

Which produces something like:

I would like the box outlines to be black without any fill or changes in the color palette.

Answer 1

You have to set edgecolor of every boxes and the use set_color for six lines (whiskers and median) associated with every box:

ax = sns.boxplot(x="day", y="total_bill", data=tips, color='white', width=.5, fliersize=0)

# iterate over boxes
for i,box in enumerate(ax.artists):
    box.set_edgecolor('black')
    box.set_facecolor('white')

    # iterate over whiskers and median lines
    for j in range(6*i,6*(i+1)):
         ax.lines[j].set_color('black')

If last cycle is applied for all artists and lines then it may be reduced to:

plt.setp(ax.artists, edgecolor = 'k', facecolor='w')
plt.setp(ax.lines, color='k')

where ax according to boxplot.

If you also need to set fliers' color follow this answer.

Answer 2

I was just exploring this and it seems there is another way to do this now. Basically, there are the keywords boxprops, medianprops, whiskerprops and (you guessed it) capprops, all of which are dictionaries that may be passed to the boxplot func. I choose to define them above and then unpack them for readability:

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns

_to_plot = pd.DataFrame(
    {
     0: np.random.normal(0,1,100),
     1: np.random.normal(0,2,100),
     2: np.random.normal(0,-1,100),
     3: np.random.normal(0,-2,100)
     }
).melt()

PROPS = {
    'boxprops':{'facecolor':'none', 'edgecolor':'red'},
    'medianprops':{'color':'green'},
    'whiskerprops':{'color':'blue'},
    'capprops':{'color':'yellow'}
}

sns.boxplot(x='variable',y='value',
            data=_to_plot,
            showfliers=False,
            linewidth=0.75, 
            **PROPS)