Pandas Dataframe Assign Value Using Previous N Row Value

Question

This is my pandas dataframe.

                     Status   
index                                    
2011-01-10 16:00:00  Active
2011-01-11 16:00:00  
2011-01-12 16:00:00  Inactive
2011-01-13 16:00:00  
2011-01-14 16:00:00     
2011-01-18 16:00:00

I would like to fill the blank value of the column 'Status' using previous N row value. The result look like following.

                     Status   
index                                    
2011-01-10 16:00:00  Active
2011-01-11 16:00:00  Active
2011-01-12 16:00:00  Inactive
2011-01-13 16:00:00  Inactive
2011-01-14 16:00:00  Inactive   
2011-01-18 16:00:00  Inactive

What's the best way to do?

are those empty rows? if they are, you can convert to null values (np.nan) and downward fill using fillna — sammywemmy
– sammywemmy, Commented Mar 13, 2020 at 5:38
Does this answer your question? Pandas(Python) : Fill empty cells with with previous row value? — Shaido
– Shaido, Commented Mar 13, 2020 at 5:48

sammywemmy · Accepted Answer · 2020-03-13 05:45:56Z

3

if the rows are already null, then forward fill should be sufficient:

  df.ffill()

if the rows are empty string, then replace with np.nan, and forward fill:

  df.replace('',np.nan).ffill()


                       status
 index  
2011-01-10 16:00:00    Active
2011-01-11 16:00:00    Active
2011-01-12 16:00:00    Inactive
2011-01-13 16:00:00    Inactive
2011-01-14 16:00:00    Inactive
2011-01-18 16:00:00    Inactive

answered Mar 13, 2020 at 5:45

sammywemmy

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