I have a graph represented as a numpy boolean array (G.adj.dtype == bool). This is homework in writing my own graph library, so I can't use networkx. I want to dump it to a file so that I can fiddle with it, but for the life of me I can't work out how to make numpy dump it in a recoverable fashion.

I've tried G.adj.tofile, which wrote the graph correctly (ish) as one long line of True/False. But fromfile barfs on reading this, giving a 1x1 array, and loadtxt raises a ValueError: invalid literal for int. np.savetxt works but saves the matrix as a list of 0/1 floats, and loadtxt(..., dtype=bool) fails with the same ValueError.

Finally, I've tried networkx.from_numpy_matrix with networkx.write_dot, but that gave each edge [weight=True] in the dot source, which broke networkx.read_dot.

To save:

numpy.savetxt('arr.txt', G.adj, fmt='%s')

To recover:

G.adj = numpy.genfromtxt('arr.txt', dtype=bool)

HTH!