判断点在哪个线段上就行了吧. 点在首尾之间,点在线上.
如果点不一定完全在线上. 那就点在首尾之间,点到线的距离最短.

你好，我并没有太了解你的意思，你可以看看这个是不是你想要的。

import numpy as np


def distance_point_to_segment(px, py, ax, ay, bx, by):
    """计算点(px, py)到线段(ax, ay)和(bx, by)的最短距离"""
    # 线段的长度
    ab = np.array([bx - ax, by - ay])
    ap = np.array([px - ax, py - ay])
    bp = np.array([px - bx, py - by])

    # 线段的长度的平方
    ab_squared = np.dot(ab, ab)

    # 计算投影比例
    if ab_squared == 0:
        return np.linalg.norm(ap)

    t = np.clip(np.dot(ap, ab) / ab_squared, 0, 1)  # 计算t值并限制范围
    projection = np.array([ax, ay]) + t * ab  # 求投影点
    return np.linalg.norm(np.array([px, py]) - projection)  # 返回距离


def find_current_stage(coordinate, route):
    """返回当前阶段"""
    current_x, current_y = coordinate
    closest_stage = None
    min_distance = float('inf')  # 用于追踪最小距离

    for index, stage in enumerate(route):
        start = stage['polyline'][0]
        end = stage['polyline'][-1]

        # 计算当前坐标到该阶段的线段的距离
        dist = distance_point_to_segment(current_x, current_y, start[0], start[1], end[0], end[1])

        # 输出调试信息
        print(f"阶段 {index + 1} 的距离: {dist:.2f} 米")

        # 如果距离小于最小距离和判断阈值，更新当前阶段
        if dist < min_distance and dist < 10:  # 修改阈值为10米
            min_distance = dist
            closest_stage = (index + 1, stage['instruction'])

    return closest_stage if closest_stage else (None, None)


# 示例坐标
current_coordinate = (121.585851, 31.198207)
route = [
    {
        'instruction': '向东步行84米左转',
        'action': '左转',
        'polyline': [
            [121.585851, 31.198207],
            [121.586424, 31.198312],
            [121.586424, 31.198312],
            [121.586727, 31.198364],
        ],
    },
    {
        'instruction': '向北步行27米右转',
        'action': '右转',
        'polyline': [
            [121.586727, 31.198364],
            [121.58668, 31.198611],
        ],
    },
    {
        'instruction': '沿晨晖路向东步行26米左转',
        'action': '左转',
        'polyline': [
            [121.586675, 31.198611],
            [121.586784, 31.198633],
            [121.586944, 31.198659],
        ],
    },
    {
        'instruction': '沿松涛路向北步行333米右转',
        'action': '右转',
        'polyline': [
            [121.586944, 31.198659],
            [121.586671, 31.200204],
            [121.586671, 31.200204],
            [121.586589, 31.20066],
            [121.586589, 31.20066],
            [121.586506, 31.201137],
            [121.586506, 31.201137],
            [121.586437, 31.201502],
            [121.586437, 31.201502],
            [121.586411, 31.201615],
            [121.586389, 31.201641],
        ],
    },
    {
        'instruction': '沿祖冲之路向东步行97米到达目的地',
        'action': '',
        'polyline': [
            [121.586385, 31.201641],
            [121.586814, 31.201719],
            [121.586814, 31.201719],
            [121.587248, 31.201793],
            [121.587248, 31.201793],
            [121.5874, 31.201819],
        ],
    },
]

current_stage, instruction = find_current_stage(current_coordinate, route)
print(f"当前阶段: {current_stage}, 指令: {instruction}")