How to show the y-axis of seaborn displot as percentage

Question

I'm using seaborn.displot to display a distribution of scores for a group of participants.

Is it possible to have the y axis show an actual percentage (example below)?

This is required by the audience for the data. Currently it is done in excel but It would be more useful in python.

import seaborn as sns

data = sns.load_dataset('titanic')

p = sns.displot(data=data, x='age', hue='sex', height=4, kind='kde')

Desired Format

Answer 1

• seaborn.displot is a figure-level plot providing access to several approaches for visualizing the univariate or bivariate distribution of data (histplot, kdeplot, ecdfplot)
• See How to plot percentage with seaborn distplot / histplot / displot
• seaborn histplot and displot output doesn't match is relevant for the settings of the common_bins and common_norm.
• Tested in python 3.8.12, pandas 1.3.4, matplotlib 3.4.3, seaborn 0.11.2
  • data is a pandas dataframe, and seaborn is an API for matplotlib.

kind='hist': seaborn.histplot

• Use stat='percent' → available from seaborn 0.11.2

import seaborn as sns
from matplotlib.ticker import PercentFormatter

data = sns.load_dataset('titanic')

p = sns.displot(data=data, x='age', stat='percent', hue='sex', height=4, kde=True, kind='hist')

Don't do the following, as explained

kind='kde': seaborn.kdeplot

• As per mwaskom, the creator of seaborn: you can wrap a percent formatter around a density value (as shown in the following code), but it's incorrect because the density is not a proportion (you may end up with values > 100%).
• As per JohanC, you can't view the y-axis as a percentage, it is a density. The density can go arbitrarily high or low, depending on the x-axis. Formatting it as a percentage is a mistake.
• I will leave this as part of the answer as an explanation, otherwise it will just be posted by someone else.
• Using matplotlib.ticker.PercentFormatter to convert the axis values.

import seaborn as sns
from matplotlib.ticker import PercentFormatter

data = sns.load_dataset('titanic')

p = sns.displot(data=data, x='age', hue='sex', height=3, kind='kde')

p.axes.flat[0].yaxis.set_major_formatter(PercentFormatter(1))

Answer 2

As mentioned by @JohanC, the y axis for a KDE is a density, not a proportion, so it does not make sense to convert it to a percentage.

You'd have two options. One would be to plot a KDE curve over a histogram with histogram counts expressed as percentages:

sns.displot(
    data=tips, x="total_bill", hue="sex",
    kind="hist", stat="percent", kde=True,
)

But your "desired plot" actually doesn't look like a density at all, it looks like a histogram plotted with a line instead of bars. You can get that with element="poly":

sns.displot(
    data=tips, x="total_bill", hue="sex",
    kind="hist", stat="percent", element="poly", fill=False,
)