Pandas 时间序列 Plot：辅助 y 轴 Label，设置下限

Question

I would like to have a time series plot including 2 columns - which works fine the way described below. I tried many ways to introduce a label for the secondary y axis with no success.

df.plot(kind='line',
    x='measurement_date',
    y=['crack_total', "crack_inv_vel"],
    secondary_y=["crack_inv_vel"],
    xlabel="date",
    ylabel="crack width [m]",
    title="crack survey")

Example Plot as produced with the code above:-

Answer 1

Assign the return value of df.plot to a variable; it will be of type matplotlib.axes._subplots.AxesSubplot . Then twinx it to get access to the secondary y-axis. Then you can adjust label etc.:

ax = df.plot(kind="line",
             x="measurement_date",
             y=["crack_total", "crack_inv_vel"],
             secondary_y=["crack_inv_vel"],
             xlabel="date",
             ylabel="crack width [m]",
             title="crack survey")

ax_secondary = ax.twinx()
ax_secondary.set_ylabel("secondary y-label")