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import math
def distance_point_line(p, l1, l2):
# (x - l1.x) * (l2.y-l1.y)/(l2.x-l1.x) + l1.y = y
# x * (l2.y-l1.y)/(l2.x-l1.x) - l1.x * (l2.y-l1.y)/(l2.x-l1.x) + l1.y - y = 0
# x * (l2.y-l1.y) - l1.x * (l2.y-l1.y) + l1.y * (l2.x-l1.x) - y * (l2.x-l1.x) = 0
# ax + by + c = 0
# with a = (l2.y-l1.y), b = -(l2.x-l1.x), c = l1.y * (l2.x-l1.x) - l1.x * (l2.y-l1.y)
a = (l2.y-l1.y)
b = -(l2.x-l1.x)
c = l1.y * (l2.x-l1.x) - l1.x * (l2.y-l1.y)
d = math.sqrt(a**2 + b**2)
a/=d
b/=d
c/=d
assert (abs(a*l1.x + b*l1.y + c) < 0.001)
assert (abs(a*l2.x + b*l2.y + c) < 0.001)
return abs(a*p.x + b*p.y + c)
def is_colinear(points, epsilon=1):
for point in points:
if distance_point_line(point, points[0], points[-1]) > epsilon:
return False
return True
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