list not working

[Zman350x]

    from __future__ import division
    import time, math

    List = [3,4,6]

    MADlist = List
    for i in range(len(MADlist)):
      MADlist[i] -= mean
      MADlist[i] = math.fabs(MADlist[i])
    MADsum = float(sum(MADlist))
    MAD = MADsum/(len(MADlist))

Here's my code.

I have a list called List. I want to make some changes without actually changing List, so I create another list, MADlist, to make changes to while keeping the original list the same. For whatever reason, it makes the same changes to the original list too! Why?

[Larz60+]

Never name a list List it's not a good idea.
It's like naming your baby 'human'.
The MADList is a pointer or reference to List, it's not a copy of list.
You can do it this way:

MADLList = []
for item in List:
    MADList.append(item)

[Zman350x]

Thanks, it worked

I'll keep the naming in mind next time