I have a question regarding how to find a column that has X element in each row. For example, a= [ 1 2 3 4 5 2 1 4 3 5 3 4 5 1 2]

I would like to find a column that has element 2 in each row. My goal is to turn out data (from the above example) [2 1 5] which means [column 2, column 1, column 5]