[104.066332, 30.640529], [104.066383, 30.639530], [104.066400, 30.638530], [104.066451, 30.637531],
[104.066468, 30.636532], [104.066518, 30.635533], [104.066535, 30.634533], [104.066586, 30.633534],
[104.066636, 30.632536], [104.066686, 30.631537], [104.066735, 30.630538], [104.066785, 30.629539],
[104.066802, 30.628539], [104.066820, 30.627540], [104.066871, 30.626541], [104.066888, 30.625541],
[104.066906, 30.624541], [104.066924, 30.623541], [104.066942, 30.622542], [104.066960, 30.621542],
[104.067011, 30.620543], [104.066122, 30.620086], [104.065124, 30.620021], [104.064124, 30.620022],
[104.063124, 30.619990], [104.062125, 30.619958], [104.061125, 30.619926], [104.060126, 30.619894],
[104.059126, 30.619895], [104.058127, 30.619928], [104.057518, 30.620722], [104.057625, 30.621716],
[104.057735, 30.622710], [104.057878, 30.623700], [104.057984, 30.624694], [104.058094, 30.625688],
[104.058204, 30.626682], [104.058315, 30.627676], [104.058425, 30.628670], [104.058502, 30.629667],
[104.058518, 30.630667], [104.058503, 30.631667], [104.058521, 30.632666], [104.057664, 30.633182],
[104.056664, 30.633174], [104.055664, 30.633166], [104.054672, 30.633289], [104.053758, 30.633694],
[104.052852, 30.634118], [104.052623, 30.635091], [104.053145, 30.635945], [104.053675, 30.636793],
[104.054200, 30.637643], [104.054756, 30.638475], [104.055295, 30.639317], [104.055843, 30.640153],
[104.056387, 30.640993], [104.056933, 30.641830], [104.057478, 30.642669], [104.058023, 30.643507],
[104.058595, 30.644327], [104.059152, 30.645158], [104.059663, 30.646018], [104.060171, 30.646879],
[104.061170, 30.646855], [104.062168, 30.646781], [104.063167, 30.646823], [104.064167, 30.646814],
[104.065163, 30.646725], [104.066157, 30.646618], [104.066231, 30.645620], [104.066247, 30.644621], ])
垂距限值法
垂距限值法其实和DP算法原理一样，但是垂距限值不是从全体角度思索，而是依次扫描每一个点，反省能否契合要求。
算法进程如下:
以第二个点末尾，计算第二个点到前一个点和后一个点所在直线的距离d;
假设d大于阈值，则保留第二个点，计算第三个点到第二个点和第四个点所在直线的距离d;若d小于阈值则舍弃第二个点，计算第三个点到第一个点和第四个点所在直线的距离d;
依次类推，直线曲线上倒数第二个点。
下面是Python代码完成：
# -*- coding: utf-8 -*-
"""
-------------------------------------------------
File Name： LimitVerticalDistance
Description : 垂距限值抽稀算法
Author : J_hao
date： 2017/8/17
-------------------------------------------------
Change Activity:
2017/8/17:
-------------------------------------------------
"""
from __future__ import division
from math import sqrt, pow
__author__ = 'J_hao'
THRESHOLD = 0.0001 # 阈值
def point2LineDistance(point_a, point_b, point_c):
"""
计算点a到点b c所在直线的距离
:param point_a:
:param point_b:
:param point_c:
:return:
"""
# 首先计算b c 所在直线的斜率和截距
if point_b[0] == point_c[0]:
return 9999999
slope = (point_b[1] - point_c[1]) / (point_b[0] - point_c[0])
intercept = point_b[1] - slope * point_b[0]
# 计算点a到b c所在直线的距离
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