structure.py 文件源码

def triangular_to_square(grid, triangle):
    """Convert a packed triangular matrix to a square matrix.

    Args:
        grid: A 3 x K array as returned by make_complete_graph().
        triangle: A length-K array.

    Returns:
        A square symmetric V x V array with zero on the diagonal.
    """
    K = len(triangle)
    assert grid.shape == (3, K)
    V = int(round(0.5 + (0.25 + 2 * K)**0.5))
    assert K == V * (V - 1) // 2
    square = np.zeros([V, V], dtype=triangle.dtype)
    square[grid[1, :], grid[2, :]] = triangle
    square[grid[2, :], grid[1, :]] = triangle
    return square