2048 Game in Python

2048.py

import curses
from random import randrange, choice
from collections import defaultdict

# Initialize the game
actions = ['Up', 'Down', 'Left', 'Right']
keys = [ord('w'), ord('s'), ord('a'), ord('d')]
actions_dict = dict(zip(keys, actions))


def transpose(field):
    return [list(row) for row in zip(*field)]


def invert(field):
    return [row[::-1] for row in field]


class Game2048:
    def __init__(self, size=4, win_value=2048):
        self.size = size
        self.win_value = win_value
        self.reset()

    def reset(self):
        self.score = 0
        self.board = [[0] * self.size for _ in range(self.size)]
        self.spawn()
        self.spawn()

    def spawn(self):
        new_element = 4 if randrange(100) > 89 else 2
        (i, j) = choice([(i, j) for i in range(self.size) for j in range(self.size) if self.board[i][j] == 0])
        self.board[i][j] = new_element

    def move(self, direction):
        def move_row_left(row):
            def tighten(row):
                new_row = [i for i in row if i != 0]
                new_row += [0] * (len(row) - len(new_row))
                return new_row

            def merge(row):
                pair = False
                new_row = []
                for i in range(len(row)):
                    if pair:
                        new_row.append(2 * row[i])
                        self.score += 2 * row[i]
                        pair = False
                    else:
                        if i + 1 < len(row) and row[i] == row[i + 1]:
                            pair = True
                            new_row.append(0)
                        else:
                            new_row.append(row[i])
                return new_row

            return tighten(merge(tighten(row)))

        moves = {}
        moves['Left'] = lambda field: [move_row_left(row) for row in field]
        moves['Right'] = lambda field: invert(moves['Left'](invert(field)))
        moves['Up'] = lambda field: transpose(moves['Left'](transpose(field)))
        moves['Down'] = lambda field: transpose(moves['Right'](transpose(field)))

        if direction in moves:
            if self.move_possible(direction):
                self.board = moves[direction](self.board)
                self.spawn()
                return True
            else:
                return False

    def move_possible(self, direction):
        def row_left_possible(row):
            def change(i):
                if row[i] == 0 and row[i + 1] != 0:
                    return True
                if row[i] != 0 and row[i] == row[i + 1]:
                    return True
                return False

            return any(change(i) for i in range(len(row) - 1))

        checks = {}
        checks['Left'] = lambda field: any(row_left_possible(row) for row in field)
        checks['Right'] = lambda field: checks['Left'](invert(field))
        checks['Up'] = lambda field: checks['Left'](transpose(field))
        checks['Down'] = lambda field: checks['Right'](transpose(field))

        if direction in checks:
            return checks[direction](self.board)
        else:
            return False

    def is_game_over(self):
        return all(self.move_possible(action) is False for action in actions)

    def is_win(self):
        return any(any(tile >= self.win_value for tile in row) for row in self.board)

    def draw(self, screen):
        help_string1 = '(W)Up (S)Down (A)Left (D)Right'
        help_string2 = '    R)Restart (Q)Exit'
        win_string = '         You Win!'

        def cast(string):
            screen.addstr(string + '\n')

        def draw_separator():
            cast('+------' * self.size + '+')

        def draw_row(row):
            cast(''.join('|{: ^6} '.format(num) if num > 0 else '|      ' for num in row) + '|')

        screen.clear()
        cast('SCORE: ' + str(self.score))

        if self.is_win():
            screen.addstr(win_string)
        else:
            if self.is_game_over():
                cast('         Game Over!')
            else:
                cast('')
        draw_separator()
        for row in self.board:
            draw_row(row)
            draw_separator()
        cast(help_string1)
        cast(help_string2)

    def play(self, screen):
        def get_user_action(screen):
            char = 'N'
            while char not in actions_dict:
                char = screen.getch()
            return actions_dict[char]

        self.reset()
        self.draw(screen)
        while True:
            action = get_user_action(screen)
            if action == 'Restart':
                self.reset()
            elif action == 'Exit':
                break
            elif self.move(action):
                if self.is_win():
                    self.draw(screen)
                    break
            self.draw(screen)


def main(stdscr):
    game = Game2048()
    game.play(stdscr)


curses.wrapper(main)