Get column name based on condition in pandas

Question

I have a dataframe as below:

I want to get the name of the column if column of a particular row if it contains 1 in the that column.

e.g.

For Ro         


        

Answer 1

Use DataFrame.dot:

df1 = df.dot(df.columns)

If there is multiple 1 per row:

df2 = df.dot(df.columns + ';').str.rstrip(';')