我有以下数据框：
Date A B
0 2017-05-31 17453139 5.865738
1 2017-06-30 17425164 5.272728
2 2017-07-31 17480789 4.843094
当我运行这个时：
df.plot(x='Date', y='A')
df.B.plot(secondary_y=True)
我收到以下错误：
> appdata\local\programs\python\python36\lib\site-packages\pandas\plotting\_timeseries.py
> in format_dateaxis(subplot, freq, index)
> 335 TimeSeries_TimedeltaFormatter())
> 336 else:
> --> 337 raise TypeError('index type not supported')
> 338
> 339 pylab.draw_if_interactive()
>
> TypeError: index type not supported
And my graph looks like this underneath the error (blue and red should overlap):
Use secondary_y in pandas.DataFrame.plot https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.plot.html:
ax = df.plot('Date', 'A')
df.plot('Date', 'B', secondary_y=True, ax=ax)
更简洁地说：
ax = df.plot(x='Date', y=['A', 'B'], secondary_y='B', figsize=(8, 5))
# move the legend for each y axis
ax.legend(bbox_to_anchor=(1.05, 0.53), loc='center left', frameon=False)
ax.right_ax.legend(bbox_to_anchor=(1.05, 0.47), loc='center left', frameon=False)
（可选）使用ax.twinx()
ax = df.plot('Date','A')
ax1 = ax.twinx()
df.plot('Date','B',ax=ax1, color='r')
Output: