Pandas: groupby forward fill with datetime index
One way is to use the transform function to fill the value column after group by: import pandas as pd a[‘value’] = a.groupby(‘company’)[‘value’].transform(lambda v: v.ffill()) a # company value #level_1 #2010-01-01 a 1.0 #2010-01-01 b 12.0 #2011-01-01 a 2.0 #2011-01-01 b 12.0 #2012-01-01 a 2.0 #2012-01-01 b 14.0 To compare, the original data frame looks … Read more