I am trying a apply a lambda function to a pandas data frame. My question is how can I apply a lambda function to column a based on value in column b using if statement.
A B C
2 5 7
4 5 9
6 7 9
df['B'].apply(lambda x: x+3 if x<(#the value in column C) else x)
You need to call apply on the dataframe, with axis=1, instead of on the B column:
>>> df.apply(lambda x: x['B']+3 if x['B']<x['C'] else x['B'], axis=1)
0 8
1 8
2 10
dtype: int64
But, a much more efficient (faster) way would be to do this:
>>> df['B'] + df['B'].lt(df['C']) * 3
0 8
1 8
2 10
dtype: int64