New submission from John K. <khoodolp...@gmail.com>:
map(f, itr) is supposed to be the lazy way to do [f(val) for val in itr]. However, when unpacking and zipping a list of maps, I get a different result from when evaluating eagerly. More precisely: Python 3.10.2 | packaged by conda-forge | (main, Mar 8 2022, 15:53:57) [GCC 9.4.0] on linux Type "help", "copyright", "credits" or "license" for more information. >>> maps = [map(lambda x: x**i, range(7)) for i in range(5)] >>> for z in zip(*maps): ... print(z) ... (0, 0, 0, 0, 0) (1, 1, 1, 1, 1) (16, 16, 16, 16, 16) (81, 81, 81, 81, 81) (256, 256, 256, 256, 256) (625, 625, 625, 625, 625) (1296, 1296, 1296, 1296, 1296) >>> lists = [[x**i for x in range(7)] for i in range(5)] >>> for z in zip(*lists): ... print(z) ... (1, 0, 0, 0, 0) (1, 1, 1, 1, 1) (1, 2, 4, 8, 16) (1, 3, 9, 27, 81) (1, 4, 16, 64, 256) (1, 5, 25, 125, 625) (1, 6, 36, 216, 1296) ---------- components: Interpreter Core messages: 415256 nosy: khoodolphin priority: normal severity: normal status: open title: Incorrect behaviour when zipping a bunch of maps type: behavior versions: Python 3.10 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue47028> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
