Filling missing values using forward and backward fill in pandas dataframe (ffill and bfill)

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You can use ffill and bfill if need replace NaN values forward and backward filling:

print (df)
                         A         B
DateTime                            
01-01-2017 03:27       NaN       NaN
01-01-2017 03:28       NaN       NaN
01-01-2017 03:29  0.181277 -0.178836
01-01-2017 03:30  0.186923 -0.183261
01-01-2017 03:31       NaN       NaN
01-01-2017 03:32       NaN       NaN
01-01-2017 03:33  0.181277 -0.178836

data = df.ffill().bfill()
print (data)
                         A         B
DateTime                            
01-01-2017 03:27  0.181277 -0.178836
01-01-2017 03:28  0.181277 -0.178836
01-01-2017 03:29  0.181277 -0.178836
01-01-2017 03:30  0.186923 -0.183261
01-01-2017 03:31  0.186923 -0.183261
01-01-2017 03:32  0.186923 -0.183261
01-01-2017 03:33  0.181277 -0.178836

Which is same as the function fillna with parameters:

data = df.fillna(method='ffill').fillna(method='bfill')

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