forward fill example

ForwardFill.py

import pandas as pd
df = pd.DataFrame([[1, 2, 3], [None, None, 6], [None, 9, None]])
print(df)
'''
     0    1    2
0  1.0  2.0  3.0
1  NaN  NaN  6.0
2  NaN  9.0  NaN
'''

df1 = df[1].fillna(method='ffill')
print(df1)
'''
     0    1    2
0  1.0  2.0  3.0
1  NaN  2.0  6.0
2  NaN  9.0  NaN
'''

df1 = df.fillna(method='ffill')
print(df1)
'''
     0    1    2
0  1.0  2.0  3.0
1  1.0  2.0  6.0
2  1.0  9.0  6.0
'''

df[0].fillna(method='ffill',limit=1 , inplace=True)
print(df)
'''
     0    1    2
0  1.0  2.0  3.0
1  1.0  NaN  6.0
2  NaN  9.0  NaN
'''