Created
September 20, 2021 02:47
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Ramer Douglas Peucker Algorithm
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from math import sqrt | |
def distance(a, b): | |
return sqrt((a[0] - b[0]) ** 2 + (a[1] - b[1]) ** 2) | |
def point_line_distance(point, start, end): | |
if (start == end): | |
return distance(point, start) | |
else: | |
n = abs( | |
(end[0] - start[0]) * (start[1] - point[1]) - | |
(start[0] - point[0]) * (end[1] - start[1]) | |
) | |
d = sqrt( | |
(end[0] - start[0]) ** 2 + (end[1] - start[1]) ** 2 | |
) | |
return n / d | |
def rdp(pointList, epsilon): | |
dmax = 0.0 | |
index = 0 | |
for i in range(1, len(pointList) - 1): | |
d = point_line_distance(pointList[i], pointList[0], pointList[-1]) | |
if d > dmax: | |
index = i | |
dmax = d | |
if dmax >= epsilon: | |
resultList = rdp(pointList[:index+1], epsilon)[:-1] + rdp(pointList[index:], epsilon) | |
else: | |
resultList = [pointList[0], pointList[-1]] | |
return resultList | |
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