Checking if a point is inside a polygon
geometry, point, polygon, python
Solution
I would suggest using the `Path` class from `matplotlib`
import matplotlib.path as mplPath
import numpy as np
poly = [190, 50, 500, 310]
bbPath = mplPath.Path(np.array([[poly[0], poly[1]],
[poly[1], poly[2]],
[poly[2], poly[3]],
[poly[3], poly[0]]]))
bbPath.contains_point((200, 100))
(There is also a `contains_points` function if you want to test for multiple points)
Problem
I have a class describing a Point (has 2 coordinates x and y) and a class describing a Polygon which has a list of Points which correspond to corners (self.corners) I need to check if a Point is in a Polygon Here is the function that is supposed to check if the Point is in the Polygon. I am using the Ray Casting Method ``` def in_me(self, point): result = False n = len(self.corners) p1x = int(self.corners[0].x) p1y = int(self.corners[0].y) for i in range(n+1): p2x = int(self.corners[i % n].x) p2y = int(self.corners[i % n].y) if point.y > min(p1y,p2y): if point.x <= max(p1x,p2x): if p1y != p2y: xinters = (point.y-p1y)*(p2x-p1x)/(p2y-p1y)+p1x print xinters if p1x == p2x or point.x <= xinters: result = not result p1x,p1y = p2x,p2y return result ``` I run a test with following shape and point: ``` PG1 = (0,0), (0,2), (2,2), (2,0) point = (1,1) ``` The script happily returns False even though the point it within the line. I am unable to find the mistake