New submission from Matthew Tanous: If I produce a list in this fashion:
l = [[x] * n] * n I would expect that I would obtain a matrix-like structure. Instead, I get a list of the *same* list, such that the statement: l[x][y] = z would change, in essence, every value in "column" y. This is different from the case where the list contains a string or integer value, where the new list points to separate instances of the internal values. In my view, this is strange and counter-intuitive behavior. If I want to create a matrix-like set to None to start, instead of using: mat = [[None] * N] * N I have to use: mat = [[None] * N for i in range(N)] If there is any possibility for it to be changed, I think that would improve things considerably. In almost no cases, in my opinion, would I want a list of lists that are forced to be the same. ---------- components: Interpreter Core messages: 266475 nosy: Matthew Tanous priority: normal severity: normal status: open title: nested list produced with multiplication is linked to the same list versions: Python 2.7, Python 3.5 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue27135> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
