# Create 4x4 grid graph
G = nx.grid_2d_graph(4,4)
G.nodes

    # Here you can see that nodes are just points with coordinates
    NodeView(((0, 1), (1, 2), (3, 2), (0, 0), (3, 3), (3, 0), (3, 1), (1, 1), (2, 1), (0, 2), (2, 0), (1, 3), (2, 3), (2, 2), (1, 0), (0, 3)))

# Set all weights to 1
for edge in G.edges:
    G.edges[edge]['weight'] = 1

0,0    1,0


0,1    1,1

G.add_edges_from([
    ((x, y), (x+1, y+1))
    for x in range(3)
    for y in range(3)
] + [
    ((x+1, y), (x, y+1))
    for x in range(3)
    for y in range(3)
], weight=1.4)