How to edit properties of whiskers, fliers, caps, etc. in Seaborn boxplot

Question

I have created a nested boxplot with an overlayed stripplot using the Seaborn package. I have seen answers on stackoverflow regarding how to edit box properties both for individual boxes and for all boxes using ax.artists generated by sns.boxplot.

Is there any way to edit whisker, cap, flier, etc. properties using a similar method? Currently I have to manually edit values in the restyle_boxplot method of the _BoxPlotter() class in the seaborn -> categorical.py file to get from the default plot to the desired plot:

Default Plot:

Desired Plot:

Here is my code for reference:

sns.set_style('whitegrid')

fig1, ax1 = plt.subplots()


ax1 = sns.boxplot(x="Facility", y="% Savings", hue="Analysis",
             data=totalSavings)

plt.setp(ax1.artists,fill=False) # <--- Current Artist functionality

ax1 = sns.stripplot(x="Facility", y="% Savings", hue="Analysis",
                    data=totalSavings, jitter=.05,edgecolor = 'gray',
                    split=True,linewidth = 0, size = 6,alpha = .6)

ax1.tick_params(axis='both', labelsize=13)
ax1.set_xticklabels(['Test 1','Test 2','Test 3','Test 4','Test 5'], rotation=90)
ax1.set_xlabel('')
ax1.set_ylabel('Percent Savings (%)', fontsize = 14)


handles, labels = ax1.get_legend_handles_labels()
legend1 = plt.legend(handles[0:3], ['A','B','C'],bbox_to_anchor=(1.05, 1), 
                     loc=2, borderaxespad=0.)
plt.setp(plt.gca().get_legend().get_texts(), fontsize='12') 
fig1.set_size_inches(10,7)

Answer 1

For matplotlib 3.5 the rectangles for the boxes aren't stored anymore in ax2.artists, but in ax2.patches. As the background of the subplot is also stored as a rectangular patch, the list of patches needs to be filtered.

The code below further makes a few adjustments:

• the exact number of lines belonging to one boxplot is counted, as depending on the boxplot options there can be a different number of lines
• saturation=1 is used; seaborn prefers to add some desaturation to larger areas, but lines will be better visible with full saturation

import matplotlib
import matplotlib.pyplot as plt
import seaborn as sns

fig, (ax1, ax2) = plt.subplots(ncols=2, figsize=(12, 5))

sns.set_style("whitegrid")
tips = sns.load_dataset("tips")

sns.boxplot(x="day", y="total_bill", hue="smoker", data=tips, palette="Set1", ax=ax1)
sns.boxplot(x="day", y="total_bill", hue="smoker", data=tips, palette="Set1", saturation=1, ax=ax2)

box_patches = [patch for patch in ax2.patches if type(patch) == matplotlib.patches.PathPatch]
if len(box_patches) == 0:  # in matplotlib older than 3.5, the boxes are stored in ax2.artists
    box_patches = ax2.artists
num_patches = len(box_patches)
lines_per_boxplot = len(ax2.lines) // num_patches
for i, patch in enumerate(box_patches):
    # Set the linecolor on the patch to the facecolor, and set the facecolor to None
    col = patch.get_facecolor()
    patch.set_edgecolor(col)
    patch.set_facecolor('None')

    # Each box has associated Line2D objects (to make the whiskers, fliers, etc.)
    # Loop over them here, and use the same color as above
    for line in ax2.lines[i * lines_per_boxplot: (i + 1) * lines_per_boxplot]:
        line.set_color(col)
        line.set_mfc(col)  # facecolor of fliers
        line.set_mec(col)  # edgecolor of fliers

# Also fix the legend
for legpatch in ax2.legend_.get_patches():
    col = legpatch.get_facecolor()
    legpatch.set_edgecolor(col)
    legpatch.set_facecolor('None')
sns.despine(left=True)
plt.show()