How to update column value based on another value in pandas

Question

I have the below data frame

A	B
Jan	10
Feb	20
Mar	30
Apr	20

Required Output - I want to check for March from A and get its corresponding value from B and add that value to remaining B values to update the dataframe using pandas

A	B
Jan	40
Feb	50
Apr	50

Answer 1

You can find the value corresponding to 'Mar', add that value to the rest of the df, then drop the row containing 'Mar'

df.loc[df['A'] != 'Mar','B'] += df.loc[df['A'] == 'Mar', 'B'].values
df = df[df['A'] != 'Mar']

Result:

>>> df
     A   B
0  Jan  40
1  Feb  50
3  Apr  50