Note that when you aren't using hue, no legend is added as the names and colors are given by the x tick labels.

CodePudding user response：

You can add a legend manually by passing a list of the desired labels like this:

plt.legend(labels = ['type 1', 'type 2'])

here is a nice blog post on the topic: https://www.delftstack.com/howto/seaborn/legend-seaborn-plot/