Python matplotlib / Seaborn stripplot with connection between points

Question

I'm using Python 3 and Seaborn to make categorical stripplots (see code and image below).

Each stripplot has 2 data points (one for each gender).

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


df = [["city2", "f", 300],
    ["city2", "m", 39],
    ["city1", "f", 95],
    ["city1", "m", 53]]

df = pd.DataFrame(df, columns = ["city", "gender", "variable"])

sns.stripplot(data=df,x='city',hue='gender',y='variable', size=10, linewidth=1)

I get the following output

However, I would like to have a line segment connecting the male and female points. I would like the figure to look like this (see pic below). However, I manually drew those red lines and I'm wondering if there is a simple way to do it w/ Seaborn or matplotlib. Thank you!

Answer 1

You can create a list of f-m pairs using pandas.dataframe.groupby and then plot the segments between pairs:

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


df = [["city2", "f", 300],
      ["city2", "m", 39],
      ["city1", "f", 95],
      ["city1", "m", 53],
      ["city4", "f", 200],
      ["city3", "f", 100],
      ["city4", "m", 236],
      ["city3", "m", 20],]


df = pd.DataFrame(df, columns = ["city", "gender", "variable"])


ax = sns.stripplot(data=df,x='city',hue='gender',y='variable', size=10, linewidth=1)

lines = ([[x, n] for n in group] for x, (_, group) in enumerate(df.groupby(['city'], sort = False)['variable']))
lc = mc.LineCollection(lines, colors='red', linewidths=2)    
ax.add_collection(lc)

sns.plt.show()

Output: