calculatin of centroid of a polygon in python

get_polygon_centroid.py

#!/usr/bin/env python3
# calculatin of centroid of a polygon
# original: https://stackoverflow.com/a/43747218/2848530
# 04/2022 created


from typing import List

class Point:
    def __init__(self, x: float, y: float):
        self.x = x
        self.y = y
    def __repr__(self):
        return f"Point({self.x}, {self.y})"


def get_polygon_centroid(pts: List[Point]) -> Point:
    first = pts[0]
    last = pts[-1]
    if first.x != last.x or first.y != last.y:
        pts = pts.copy()
        pts.append(first)
    twicearea = 0
    x = 0
    y = 0
    nPts = len(pts)
    i = 0
    j = nPts - 1
    while i < nPts:
        p1 = pts[i]
        p2 = pts[j]
        f = (p1.y - first.y) * (p2.x - first.x) - (p2.y - first.y) * (p1.x - first.x)
        twicearea += f
        x += (p1.x + p2.x - 2 * first.x) * f
        y += (p1.y + p2.y - 2 * first.y) * f

        j = i
        i += 1

    f = twicearea * 3

    return Point(x / f + first.x, y / f + first.y)


# ---------- MAIN ------------

pts = [
    Point(78.0001462, 40.0008827),
    Point(78.0000228, 40.0008940),
    Point(78.0000242, 40.0009264),
    Point(78.0001462, 40.0008827),
]

c = get_polygon_centroid(pts)

print(c) # --> Point(78.0000644, 40.000901033333335)