Starting from a dataframe df:
U L
111 en
112 en
112 es
113 es
113 ja
113 zh
114 es
Imagine you want to add a new column called S taking values from the following dictionary:
d = {112: 'en', 113: 'es', 114: 'es', 111: 'en'}
You can use map to perform a lookup on keys returni...
