Multiplying columns with NULL values

Question

I am trying to write a python code where I multiply a column value across the other columns. However, some values are NULL in my one C column. I am having a hard time how to program that if a value is NULL switch it to 1.

A     B     C         Result should be:    X    Y
5     3     2                              10   6
10    6                                    10   6
15    9                                    15   9
20    12    8                              160  96  

This is the python code I have tried:

if df[C] is NONE:
    df[X] = df[A]*1
else:
    df[X] = df[A]*df[C]

And so on with df[B] as well. But, it still gives me blanks in the excel rather than the "10 & 6" and "15 & 9" I need.

Results I get with my code:

X     Y
10    6


160   96

Answer 1

You can using np.where

df
Out[97]: 
    A   B    C
0   5   3  2.0
1  10   6  NaN
2  15   9  NaN
3  20  12  8.0
np.where(df.C.isna(),df.A,df.A*df.C)
Out[98]: array([ 10.,  10.,  15., 160.])

Your if function should with for loop