How to concatenate multiple column values into a single column in Panda dataframe

Question

This question is same to this posted earlier. I want to concatenate three columns instead of concatenating two columns:

Here is the combining two columns:

Answer 1

df = DataFrame({'foo':['a','b','c'], 'bar':[1, 2, 3], 'new':['apple', 'banana', 'pear']})

df['combined'] = df['foo'].astype(str)+'_'+df['bar'].astype(str)

If you concatenate with string('_') please you convert the column to string which you want and after you can concatenate the dataframe.