How can i merge/join multiple text columns within a single pandas dataframe without concatenating the columns individually
e.g
d = pd.DataFrame({'A':['one','two','three'],'B':['London','New York','Tokyo'],'C':['UK','USA','Japan'],'D':['Hot','Hot','Cold']})
the output should be
0 one London UK Hot
1 two New York USA Hot
2 three Tokyo Japan Cold
Name: combined, dtype: object