I have an N x N Numpy array.
I need to manipulate the ith column in a paricular way, and the remaining columns in a different but common way. How do i do this in a numpythonic manner. The parameter i is passed to the function to be used.

Example:

```
a=np.zeros([4,4])

```

Now, we need 1st,2nd and 4th, say to be squared element wise.
3rd one to be cubed elementwise.