import numpy as np

def _side(p, a, b):
    return np.sign((b[0] - a[0]) * (p[1] - a[1]) - (b[1] - a[1]) * (p[0] - a[0]))

def _point_to_segment_dist(px, py, ax, ay, bx, by):
    A = np.array([ax, ay], dtype=float)
    B = np.array([bx, by], dtype=float)
    P = np.array([px, py], dtype=float)
    AB = B - A
    t = np.clip(np.dot(P - A, AB) / np.dot(AB, AB), 0, 1)
    return np.linalg.norm(P - (A + t * AB))