Pandas: Conditionally replace values based on other columns values

Question

I have a dataframe (df) that looks like this:

                    environment     event   
time                    
2017-04-28 13:08:22     NaN         add_rd  
         


        

Answer 1

You could consider using where:

df.environment.where((~df.environment.isnull()) & (df.event != 'add_rd'),
                     'RD', inplace=True)

If the condition is not met, the values is replaced by the second element.