python - 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 Row 1: Blanks,
For Row 2: Manufacturing,
For Row 3: Manufacturing,
For Row 4: Manufacturing,
For Row 5: Social, Finance, Analytics, Advertising,

Right now I am able to get the complete row only:

primary_sectors = lambda primary_sector: sectors[
    sectors["category_list"] == primary_sector
]

Please help me to get the name of the column in the above dataframe.

I tried this code:

primary_sectors("3D").filter(items=["0"])

It gives me output as 1 but I need output as Manufacturing

Answer 1

Use DataFrame.dot:

df1 = df.dot(df.columns)

If there is multiple 1 per row:

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