How to customize the text ticklabels for each subplot of a seaborn catplot

Question

Let us consider the following example (from Seaborn documentation):

titanic = sns.load_dataset("titanic")

fg = sns.catplot(x="age", y="embark_town",
                hue="sex", row="class",
                data=titanic[titanic.embark_town.notnull()],
                orient="h", height=2, aspect=3, palette="Set3",
                kind="violin", dodge=True, cut=0, bw=.2)

Output:

I want to change the tick labels on the y axis, for example by prepending a number in parenthesis: (1) Southampton, (2) Cherbourg, (3) Queenstown. I have seen this answer, and I have tried to use a FuncFormatter, but I obtain a strange result. Here is my code:

titanic = sns.load_dataset("titanic")

fg = sns.catplot(x="age", y="embark_town",
                hue="sex", row="class",
                data=titanic[titanic.embark_town.notnull()],
                orient="h", height=2, aspect=3, palette="Set3",
                kind="violin", dodge=True, cut=0, bw=.2)

from matplotlib.ticker import FuncFormatter
for ax in fg.axes.flat:
    ax.yaxis.set_major_formatter(ticker.FuncFormatter(lambda x, pos: f'({1 + pos}) {x}'))

And here is the output:

It looks like x is the same as pos in the lambda. I was expecting x to be the value of the tick label (i.e. Southampton, Cherbourg, Queenstown). What am I doing wrong?

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Software versions:

matplotlib                         3.4.3
seaborn                            0.11.2

Answer 1

• Similar to the answers for How to rotate xticklabels in a seaborn catplot, but requiring customized text for each tick of each subplot.
• Text labels work differently than numeric labels that are in the other example. Numeric labels match the tick position, but that is not the case for text labels.
• .get_yticklabels() gets [Text(0, 0, 'Southampton'), Text(0, 1, 'Cherbourg'), Text(0, 2, 'Queenstown')] for each subplot
• As shown below, extract the text and position, and the use .set_yticklabels to set the new text label
• Tested in python 3.8.12, matplotlib 3.4.3, seaborn 0.11.2

import seaborn as sns

titanic = sns.load_dataset("titanic")

fg = sns.catplot(x="age", y="embark_town",
                hue="sex", row="class",
                data=titanic[titanic.embark_town.notnull()],
                orient="h", height=2, aspect=3, palette="Set3",
                kind="violin", dodge=True, cut=0, bw=.2)

for ax in fg.axes.flat:  # iterate through each subplot
    labels = ax.get_yticklabels()  # get the position and text for each subplot
    for label in labels:
        _, y = label.get_position()  # extract the y tick position
        txt = label.get_text()  # extract the text
        txt = f'({y + 1}) {txt}'  # update the text string
        label.set_text(txt)  # set the text
    ax.set_yticklabels(labels)  # update the yticklabels