A Python class to describe a user polygon with a series of APLocationObjects. Can determine whether a test point (also an APLocationObject) lies within the polygon using the ray-casting algorithm. Created for my Curtin University, Masters of Geospatial Science, Spatial Computations 100, second assignment, BoreholeWrangler V3.0.

APPolygonObject.py

from APLocationObject import LocationObject

class PolygonObject:
    # Class properties
    lVertices = []
    iNumberOfVertices = None

    # Class methods
    def __init__(self, lPoints):
        self.iNumberOfVertices = len(lPoints)

        if self.iNumberOfVertices == 0:  # Polygon must have at least three points to describe an area.
            raise ValueError("Zero points provided to the PolygonObject.")
        elif 1 <= self.iNumberOfVertices <= 2:
            raise ValueError("Not enough points provided to create an area. Three points needed for an area (at a "
                             "minimum).")
        else:
            for location in lPoints:
                if isinstance(location, LocationObject):
                    self.lVertices.append(location)
                else:
                    raise TypeError("An object of a class other than LocationObject passed to the PolygonObject.")


    def determineIfPointLiesWithinPolygon(self, locationToTest):
        # SEE NEXT SNIPPET FOR IMPLEMENTATION


    def describePolygon(self):
        print "Number of vertices = " + str(self.iNumberOfVertices)

        for point in self.lVertices:
            iPointNumber = self.lVertices.index(point) + 1
            descriptionString = "Point #{0}:\t{1}\n".format(str(iPointNumber), point.describeLocation(False))
            print descriptionString