帮我写一段实现这个功能的python的代码，我有一条线段，我知道线段的两个端点坐标x1、x2、y1、y2的坐标以及一个不规则凸多边形框端点坐标数组out，我只想要这条线段在矩形框内的部分，将这条线段多余部分截掉，只留下多边形框内的部分

这是一个简单的实现，采用了矩形相交以及线段与矩形的判定方法。

import math

def line_clip(x1, y1, x2, y2, out):
    # 计算矩形边界
    min_x = min(out, key=lambda p: p[0])[0]
    max_x = max(out, key=lambda p: p[0])[0]
    min_y = min(out, key=lambda p: p[1])[1]
    max_y = max(out, key=lambda p: p[1])[1]

    # 线段是否在矩形内
    if x1 < min_x and x2 < min_x or \
       x1 > max_x and x2 > max_x or \
       y1 < min_y and y2 < min_y or \
       y1 > max_y and y2 > max_y:
        return None
    
    # 线段是否与矩形相交
    if x1 < min_x or x1 > max_x or \
       y1 < min_y or y1 > max_y or \
       x2 < min_x or x2 > max_x or \
       y2 < min_y or y2 > max_y:
        # 计算线段与矩形相交的点
        clip_points = []
        clip_points.append(line_intersect((x1, y1), (x2, y2), (min_x, min_y), (max_x, min_y)))
        clip_points.append(line_intersect((x1, y1), (x2, y2), (max_x, min_y), (max_x, max_y)))
        clip_points.append(line_intersect((x1, y1), (x2, y2), (max_x, max_y), (min_x, max_y)))
        clip_points.append(line_intersect((x1, y1), (x2, y2), (min_x, max_y), (min_x, min_y)))
        # 过滤掉无效点
        clip_points = [p for p in clip_points if p is not None and point_in_poly(p[0], p[1], out)]
        if len(clip_points) < 2:
            return None
        # 返回截断的线段
        return clip_points[0][0], clip_points[0][1], clip_points[1][0], clip_points[1][1]
    
    # 线段在矩形内，直接返回
    return x1, y1, x2, y2

def line_intersect(p1, p2, p3, p4):
    # 利用向量叉乘计算交点
    x1, y1 = p1
    x2, y2 = p2
    x3, y3 = p3
    x4, y4 = p4
    a = (y4-y3)*(x2-x1) - (x4-x3)*(y2-y1)
    if a == 0:
        return None
    t1 = ((x4-x3)*(y1-y3) - (y4-y3)*(x1-x3)) / a
    x = x1 + t1*(x2-x1)
    y = y1 + t1*(y2-y1)
    return x, y

def point_in_poly(x, y, poly):
    # 射线法判断点是否在多边形内
    crossings = 0
    for i in range(len(poly)):
        x1, y1 = poly[i]
        x2, y2 = poly[(i+1)%len(poly)]
        if y1 == y2:
            continue
        if y < min(y1, y2) or y >= max(y1, y2):
            continue
        x_cross = (y-y1)*(x2-x1)/(y2-y1) + x1
        if x < x_cross:
            crossings += 1
    return crossings % 2 == 1

# 测试
out = [(0,0), (1,1), (1,-1), (0,0)]
print(line_clip(0,-2,2,0,out))  # None
print(line_clip(0,0,1,1,out))  # (0, 0, 0.5, 0.5)
print(line_clip(0,-1,1,-1,out))  # (0.5, 0, 1, 0)
print(line_clip(0,0,2,0,out))  # (0, 0, 1, 0)