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

Another solution using DataFrame.apply(), with slightly less typing and more scalable when you want to join more columns:

cols = ['foo', 'bar', 'new']
df['combined'] = df[cols].apply(lambda row: '_'.join(row.values.astype(str)), axis=1)