Create Column with ELIF in Pandas

Question

Question

I am having trouble figuring out how to create new DataFrame column based on the values in two other columns. I need to use if/elif/else l

Answer 1

ELIF logic can be implemented with np.select or nested np.where:

import numpy as np

df['combo'] = np.select([df.mobile == 'mobile', df.tablet == 'tablet'], 
                        ['mobile', 'tablet'], 
                        default='other')
# or 
df['combo'] = np.where(df.mobile == 'mobile', 'mobile', 
                       np.where(df.tablet == 'tablet', 'tablet', 'other'))

Sample Data + Output:

   mobile  tablet   combo
0  mobile     bar  mobile
1     foo  tablet  tablet
2     foo     nan   other
3  mobile  tablet  mobile
4  mobile     nan  mobile
5     foo  tablet  tablet
6  mobile     bar  mobile
7  mobile  tablet  mobile
8  mobile     bar  mobile
9  mobile     nan  mobile