You are reading an old version of the documentation (v3.0.3). For the latest version see https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.yaxis_date.html
Version 3.0.3
matplotlib
Fork me on GitHub

matplotlib.axes.Axes.yaxis_date

Axes.yaxis_date(tz=None)

Sets up y-axis ticks and labels that treat the y data as dates.

Parameters:
tz : string or tzinfo instance, optional

Timezone string or timezone. Defaults to rc value.