Game of Life in Python

pyfe.py

from funcy import mapcat

class Pyfe:
    def __init__(self):
        self._living_cells = set()

    @property
    def living_cells(self):
        return self._living_cells

    @living_cells.setter
    def living_cells(self, cells):
        self._living_cells = cells

    def toggle(self, x, y):
        cell = (x, y)
        if cell in self._living_cells:
            self._living_cells.discard(cell)
        else:
            self._living_cells.add(cell)

    def tick(self):
        neighbors_fn = lambda x: self.neighbors_of(x)
        all_neighbors = mapcat(neighbors_fn, self.living_cells)
        neighbor_counts = self.frequencies(all_neighbors)

        alive_fn = lambda x: self.is_alive(x, neighbor_counts[x])
        next_gen = filter(alive_fn, neighbor_counts.keys())
        self._living_cells = set(next_gen)

    def neighbors_of(self, cell):
        x, y = cell
        neighbors = [(x + dx, y + dy) for dx in [-1, 0, 1] for dy in [-1, 0, 1]]
        neighbors = set(neighbors)
        neighbors.discard(cell)
        return neighbors

    def frequencies(self, cells):
        result = {}
        for cell in cells:
            if cell in result:
                freq = result[cell]
                result[cell] = freq + 1
            else:
                result[cell] = 1
        return result

    def is_alive(self, cell, neighbors):
        if neighbors == 2 and cell in self._living_cells:
            return True
        elif neighbors == 3:
            return True
        else:
            return False

# -----------------------------
# Snippet from test file

class PyfeTest(unittest.TestCase):

    def test_blinker(self):
        self._life.living_cells = {(0, 0), (1, 0), (-1, 0)}
        self._life.tick()
        self.assertEqual({(0, 0), (0, -1), (0, 1)}, self._life.living_cells)