Can you add an attribute to an attribute in a class in python?

Question

I would like to add an attribute to an existing attribute (or method if I need to). An example of this would be numpy's random method: numpy.random.rand()

In my case I have a matrix stored in the data attribute of my class: "myClass.data" that I would like to be able to easily call prespecified columns from: "Ex: myClass.data.columns"

class MyClass:
    def __init__(self, data):
        self.data = data
        self.data.columns = self.data[1:3]