pandas的subplot

N09_0027_P1['mean pupil'].plot(xlabel='date', ylabel='pupil size', kind='line', title='N09_0027_P1',ax = plt.subplot(411))
N09_0027_P2['mean pupil'].plot(xlabel='date', ylabel='pupil size', kind='line', title='N09_0027_P2',ax = plt.subplot(412))
N09_0027_P3['mean pupil'].plot(xlabel='date', ylabel='pupil size', kind='line', title='N09_0027_P3',ax = plt.subplot(413))
N09_0027_P4['mean pupil'].plot(xlabel='date', ylabel='pupil size', kind='line', title='N09_0027_P4',ax = plt.subplot(414))

 

subplot的属性怎么调整？