Using if else in python to determine whether or not to perform an operation on another cell in the same row

Question

This should be easy for anyone good at coding I am just learning and struggling with syntax. I have a data frame with 9 columns, 2 of these are 'Account Name'and 'Amount'I just want to say that if the 'Account Name' is 'CREDIT CARD' I want it to divide the value in 'Amount' by 2.

The data type for 'Account Name' is object and for 'Amount' is float 64.

Here is what I have

df.loc[df['Account Name'] == 'CREDIT CARD', 'Adjusted Amount'] = df['Amount']/2

I know this is creating a new column but I wasn't able to make it work in place either.

Answer 1

You are close, need assign output to same column Amount:

#thanks Corralien
df.loc[df['Account Name'] == 'CREDIT CARD', 'Amount'] /= 2

#working same like
df.loc[df['Account Name'] == 'CREDIT CARD', 'Amount'] = df['Amount']/2

Or if need new column use numpy.where:

df['Adjusted Amount'] = np.where(df['Account Name'] == 'CREDIT CARD',
                                 df['Amount']/2, 
                                 df['Amount'])