CODEWITHSUNDEEP
pandasdataframe
Max
Max

Reputation: 471

How to calculate values if one column is true?

let's say you have the following df:

In [1]: df15 = pd.DataFrame([[1, 2, True], [1, 3, False], [4, 6, True]], columns=['BTW', 'ExclBTW','is_na'])

Now I want to calculate a new column, taxrate#1, when the value of 'is_na' is True.

I've tried the following code:

for i, row in df15.iterrows():
    if df15.loc[i,'is_na'] == True:
        df15['taxrate#1'] = df15['BTW'].astype(float) / df15['ExclBTW'].astype(float)
    else:
        pass

However, this gets the operation on all values. Somehow I can't get the if statement to work..

Desired output:

   BTW ExclBTW  is_na   taxrate#1
0   1   2     True      0.010526
1   1   3     False     NaN
2   4   6     True      0.66

Please help!

Upvotes: 0

Views: 54

Answers (1)

Arkadiusz
Arkadiusz

Reputation: 1875

You can use numpy:

import numpy as np

df15['taxrate#1'] = np.where(df15['is_na'] == True, 
                             round(df15['BTW'] / df15['ExclBTW'], 2),
                             np.nan)

In your condition first value in output should give 0.5 if we divide BTW by ExclBTW.

Upvotes: 1

Related Questions