geospatialpython/pointinpoly.py at master · GeospatialPython/geospatialpython · GitHub

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# Determine if a point is inside a given polygon or not
# Polygon is a list of (x,y) pairs. This fuction
# returns True or False. The algorithm is called
# "Ray Casting Method".

defpoint_in_poly(x,y,poly):

n=len(poly)
inside=False

p1x,p1y=poly[0]
foriinrange(n+1):
p2x,p2y=poly[i%n]
ify>min(p1y,p2y):
ify<=max(p1y,p2y):
ifx<=max(p1x,p2x):
ifp1y!=p2y:
xinters= (y-p1y)*(p2x-p1x)/(p2y-p1y)+p1x
ifp1x==p2xorx<=xinters:
inside=notinside
p1x,p1y=p2x,p2y

returninside

## Test

polygon= [(0,10),(10,10),(10,0),(0,0)]

point_x=5
point_y=5

## Call the fuction with the points and the polygon
printpoint_in_poly(point_x,point_y,polygon)