point_in_polygon.py

def point_in_polygon(point, polygon):

    inside=False
    j=len(polygon)-1
    for i in range(len(polygon)):
        if ((polygon[i][1]>point[1])!=(polygon[j][1]>point[1]) and (point[0]<(polygon[j][0]-polygon[i][0])*(point[1]-polygon[i][1])/( polygon[j][1] - polygon[i][1] ) + polygon[i][0])):
            inside =not inside
        j=i
    return inside

if __name__ == "__main__":

    fora = (-1, -1)

    area1 = [(0,0),(0,5),(2,5),(2,4),(5,4),(5,0)]
    dentro = (1, 1)

    area2 = [(2,5),(2,4), (5, 4),(5, 5)]
    dentro_a2 = (3, 4)

    assert point_in_polygon(dentro, area1) is True
    assert point_in_polygon(fora, area1) is False

    assert point_in_polygon(dentro_a2, area2) is True
    assert point_in_polygon(fora, area2) is False