I would like to get from this:

To this:

I know I can create 4 separate DFs with name and email column, then merge all 4 and drop the ones with 'NO' but I feel there might be smarter and more dynamic solution for this.

CodePudding user response：

result = (
    df.set_index("nname")
    .stack()
    .to_frame("eemail")
    .query("eemail != 'NO'")
    .droplevel(1)
    .reset_index()
)

CodePudding user response：

Try this:

(df.mask(df.eq('NO'))
 .set_index('nname')
 .stack()
 .droplevel(1)
 .reset_index(level=0,name = 'eemail'))

Output:

   nname              eemail
0   Stan    [email protected]
1   Stan   [email protected]
2  Danny   [email protected]
3  Danny  [email protected]
4  Danny  [email protected]
5  Danny  [email protected]
6   Elle    [email protected]