New submission from Austin Green <austin.gr...@orcon.net.nz>:
Not sure if this is a bug, cannot find any clarification in the documentation. Please reassign it if need be. Using the * operator to generate a list of lists: >>> a = [[0]*3]*3 >>> a [[0, 0, 0], [0, 0, 0], [0, 0, 0]] gives a list of 3 lists of zeroes, as expected. But the data values appear to be shared, so e.g. >>> a[1][1] = 'spam' >>> a [[0, 'spam', 0], [0, 'spam', 0], [0, 'spam', 0]] Not what I was expecting! A list comprehension gives the results I wanted: >>> a = [[0 for x in range(3)] for x in range(3)] >>> a [[0, 0, 0], [0, 0, 0], [0, 0, 0]] Looks just the same, but: >>> a[1][1] = 'spam' >>> a [[0, 0, 0], [0, 'spam', 0], [0, 0, 0]] gives a different result, and is actually what I was expecting from the first example. ---------- components: Interpreter Core messages: 380101 nosy: austin.green priority: normal severity: normal status: open title: List repetition operator gives unexpected results type: behavior versions: Python 3.6 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue42223> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
