python - Creating a list of mutable items repeated N times

Question

I have a list containing a set of x mutable items. I would like to create another list where the set of x mutable items is repeated n times. However, the items must be references to unique objects rather than simply references to the original objects.

For example, let a = [[1],[2],[3]]. Suppose I would like the numbers inside to be repeated n=3 times, i.e. [[0],[2],[3],[1],[2],[3],[1],[2],[3]].

I can do this easily by using a * 3. The problem is that if I change a[0][0] = 0, then I will get a == [[0],[2],[3],[0],[2],[3],[0],[2],[3]], which is not desirable because I would like to change only the first element. Is there any other way to achieve this?

Answer 1

itertools has a method for this called repeat. Just pair it with chain.

from itertools import repeat, chain

a = [1,2,3]

b = list(chain(*repeat(a, 3)))

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>>> b
[1,2,3,1,2,3,1,2,3]