[docs]def pointInsidePolygon(x,y,poly):
'''
Determine if a point is inside a given polygon or not
Polygon is a list of (x,y) pairs.
[code taken from: http://www.ariel.com.au/a/python-point-int-poly.html]
let's make an easy square:
>>> poly = [ (0,0),\
(1,0),\
(1,1),\
(0,1) ]
>>> pointInsidePolygon(0.5,0.5, poly)
True
>>> pointInsidePolygon(1.5,1.5, poly)
False
'''
n = len(poly)
inside =False
p1x,p1y = poly[0]
for i in range(n+1):
p2x,p2y = poly[i % n]
if y > min(p1y,p2y):
if y <= max(p1y,p2y):
if x <= max(p1x,p2x):
if p1y != p2y:
xinters = (y-p1y)*(p2x-p1x)/(p2y-p1y)+p1x
if p1x == p2x or x <= xinters:
inside = not inside
p1x,p1y = p2x,p2y
return inside
if __name__ == "__main__":
import doctest
doctest.testmod()