structure.py 文件源码

def make_complete_graph(num_vertices):
    """Constructs a complete graph.

    The pairing function is: k = v1 + v2 * (v2 - 1) // 2

    Args:
        num_vertices: Number of vertices.

    Returns: A tuple with elements:
        V: Number of vertices.
        K: Number of edges.
        grid: a 3 x K grid of (edge, vertex, vertex) triples.
    """
    V = num_vertices
    K = V * (V - 1) // 2
    grid = np.zeros([3, K], np.int32)
    k = 0
    for v2 in range(V):
        for v1 in range(v2):
            grid[:, k] = [k, v1, v2]
            k += 1
    return grid