Pandas function to perform a calculation on one column, if condition is met on a different column-CodePudding

I have the following dataset

 df = pd.DataFrame([[1,1000],[2,1000],[3,1000]])
 df.columns = ["A","B"]
 df
   A  B
0  1  1000
1  2  1000
2  3  1000

I would like to create a new column C that calculates:

if A = 1 then C = B*.8
if A = 2 then C = B*.1
if A = 3 then C = B*.05
if A = 4 then C = B*.025
...
...(going up to 10)

Is it best to create a function?

def calculation(x):
    if x == 1:
        return y*0.75
    elif...

But im not quite sure how to work with multiple columns. Any help would be appreciated! Thanks

CodePudding user response：

Use Series.map by dictionary and then multiple by B column:

d = {1:.8, 2:.1, 3:.05, 4:.025}
df['C'] = df['A'].map(d).mul(df.B)