Re: [Numpy-discussion] lists of zeros and ones

On 3/19/2010 10:53 AM, gerardob wrote:

I would like to know a simple way to generate a list containing all the lists having two 1's at each element.

Example, n = 4 L2 = [[1,1,0,0],[1,0,1,0],[1,0,0,1],[0,1,1,0],[0,1,0,1],[0,0,1,1]]

I like list(set(itertools.permutations([1,1]+[0]*(n-2)))) (Modify if you don't like the tuples.) But you can use a NumPy array if you wish: cols = list(itertools.combinations(range(n),2)) r = len(cols) rows = np.arange(r)[:,None] a = np.zeros((r,n),dtype=np.int_) a[rows,cols] = 1 a.tolist() hth, Alan Isaac