def fromList(shape, coords, weights=None):
if weights is not None:
assert len(coords) == len(weights)
if len(shape) == 1:
NX = NY = shape[0]
else:
NX = shape[0]
NY = shape[1]
if weights is None:
X = [a for (a, b) in coords]
Y = [b for (a, b) in coords]
G = sps.lil_matrix((NX * NY, 1), dtype=np.float64)
lin_I = common.sub2ind((NX, NY), X, Y)
G[lin_I, 0] = 1
G = G.reshape((NX, NY))
else:
G = sps.lil_matrix((NX, NY), dtype=np.float64)
for (i, w) in enumerate(weights):
c = coords[i]
x = c[0]
y = c[1]
G[x, y] = w
return G
def create_knn_graph(N, idx, k=None):
if k is None:
k = idx.shape[1]
G = sps.lil_matrix((N * N, 1), dtype=np.float64)
for j in xrange(k): # assign entries using linear indexing
Ij = idx[:, j]
lin_I = common.sub2ind((N, N), xrange(N), Ij.T)
G[lin_I, 0] = 1
G = G.reshape((N, N))
return G
