pandas对指定列进行填充的方法

>>> import pandas as pd>>> import numpy as np>>> ts1 = [0, 1, np.nan, np.nan, np.nan, np.nan]>>> ts2 = [0, 2, np.nan, 3, np.nan, np.nan]>>> d = {'X': ts1, 'Y': ts2, 'Z': ts2}>>> df = pd.DataFrame(data=d)>>> df   X  Y  Z0 0.0 0.0 0.01 1.0 2.0 2.02 NaN NaN NaN3 NaN 3.0 3.04 NaN NaN NaN5 NaN NaN NaN>>> col =['X','Y']>>> df[col] = df[col].ffill()>>> df   X  Y  Z0 0.0 0.0 0.01 1.0 2.0 2.02 1.0 2.0 NaN3 1.0 3.0 3.04 1.0 3.0 NaN5 1.0 3.0 NaN>>>