2011/9/15 Stef Mientki <stef.mien...@gmail.com>: > hello, > > I need a nested list, like this > >>>> A= [ [None,None], [None,None], [None, None] ] >>>> A[2][0] =77 >>>> A > [[None, None], [None, None], [77, None]] > ... > > thanks, > Stef > -- > http://mail.python.org/mailman/listinfo/python-list >
Besides the above sugestions to correct the nested list approach, if you need to set and access the data at the given "coordinates" you could also use a nested defaultdict, which doesn't need to be pre-filled before setting, e.g.: >>> from collections import defaultdict as dd >>> def dd_dd(): ... return dd(dd) ... >>> dd_matrix = dd(dd_dd) >>> >>> dd_matrix[2][0] = 77 >>> dd_matrix[2][0] 77 >>> dd_matrix defaultdict(<function dd_dd at 0x04E5B8B0>, {2: defaultdict(<type 'collections.defaultdict'>, {0: 77})}) >>> However, the nested list are concise enough, I guess. Regards, vbr -- http://mail.python.org/mailman/listinfo/python-list