from types import NoneType # for tensor from copy import deepcopy # for tensor def tensor(sizes=0, elem=0): """tensor(sizes=0, elem=0): creates a list of lists of lists... The parameter sizes can be a number or a tuple/list or sizes. >>> tensor() [] >>> tensor(()) [] It works with a single number or a sequence of numbers: >>> tensor(3) [0, 0, 0] >>> tensor((3)) [0, 0, 0] >>> tensor((3), None) [None, None, None] >>> tensor((2, 3)) # array of 2 rows and 3 colums. [[0, 0, 0], [0, 0, 0]] >>> tensor((2, 3), 2) [[2, 2, 2], [2, 2, 2]] >>> tensor((1, 2, 3)) [[[0, 0, 0], [0, 0, 0]]] >>> tensor((2, 2, 3)) [[[0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0]]] It works with mutables too, calling deepcopy: >>> r = tensor((2, 3), [3]) >>> r [[[3], [3], [3]], [[3], [3], [3]]] >>> r[0][2][0] = 0 >>> r [[[3], [3], [0]], [[3], [3], [3]]] """ if isinstance(sizes, (int, long)): sizes = [sizes] elif not isinstance(sizes, list): sizes = list(sizes) result = [] if sizes: first = sizes.pop() if isinstance(elem, (int, long, basestring, tuple, NoneType, bool)): result = [elem] * first else: result = [deepcopy(elem) for i in xrange(first)] while sizes: result = [deepcopy(result) for i in xrange(sizes.pop())] return result def transpose(m): """transpose(m): transposes a 2D matrix, made of tuples or lists of tuples or lists, keeping their type. >>> transpose([]) Traceback (most recent call last): ... IndexError: list index out of range >>> transpose([[]]) [] >>> transpose([1,2,3]) Traceback (most recent call last): ... TypeError: zip argument #1 must support iteration >>> transpose([[1,2,3]]) [[1], [2], [3]] >>> transpose( [[2, 2, 2], [2, 2, 2]] ) [[2, 2], [2, 2], [2, 2]] >>> transpose( [(2, 2, 2), (2, 2, 2)] ) [(2, 2), (2, 2), (2, 2)] >>> transpose( ([2, 2, 2], [2, 2, 2]) ) ([2, 2], [2, 2], [2, 2]) >>> transpose( ((2, 2, 2), (2, 2, 2)) ) ((2, 2), (2, 2), (2, 2)) >>> t = [[[1], [2]], [[3], [4]], [[5], [6]]] >>> transpose(t) [[[1], [3], [5]], [[2], [4], [6]]] """ if isinstance(m, list): if isinstance(m[0], list): return map(list, zip(*m)) else: return zip(*m) # faster else: if isinstance(m[0], list): return tuple(map(list, zip(*m))) else: return tuple( zip(*m) ) if __name__ == "__main__": import doctest doctest.testmod() print "Tests done."