Checking if a point is inside a polygon

Question

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 t

Answer 1

I'd like to suggest some other changes there:

def contains(self, point):
    if not self.corners:
        return False

    def lines():
        p0 = self.corners[-1]
        for p1 in self.corners:
            yield p0, p1
            p0 = p1

    for p1, p2 in lines():
        ... # perform actual checks here

Notes:

• A polygon with 5 corners also has 5 bounding lines, not 6, your loop is one off.
• Using a separate generator expression makes clear that you are checking each line in turn.
• Checking for an empty number of lines was added. However, how to treat zero-length lines and polygons with a single corner is still open.
• I'd also consider making the lines() function a normal member instead of a nested utility.
• Instead of the many nested if structures, you could also check for the inverse and then continue or use and.