why does the list of list replicate this way?

why does the list of list replicate this way? - Printable Version

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why does the list of list replicate this way? - hshivaraj - Nov-30-2017

a = [[]] * 10

a
[[], [], [], [], [], [], [], [], [], []]

a[0].append((1,2))

a
[[(1, 2)], [(1, 2)], [(1, 2)], [(1, 2)], [(1, 2)], [(1, 2)], [(1, 2)], [(1, 2)], [(1, 2)], [(1, 2)]]

Why does it replicate the values across the entire list? Bizarre Huh

RE: why does the list of list replicate this way? - Windspar - Nov-30-2017

Because list are reference. [[]] * 10 makes 10 reference copies.

a = [[] for x in range(10)]

RE: why does the list of list replicate this way? - hshivaraj - Dec-01-2017

Thanks very much windspar.
That was as simple as that :)