def __init__()

in gym/envs/toy_text/cliffwalking.py [0:0]

• 34 lines of code
• 4 McCabe index (conditional complexity)

    def __init__(self, render_mode: Optional[str] = None):
        self.shape = (4, 12)
        self.start_state_index = np.ravel_multi_index((3, 0), self.shape)

        self.nS = np.prod(self.shape)
        self.nA = 4

        # Cliff Location
        self._cliff = np.zeros(self.shape, dtype=bool)
        self._cliff[3, 1:-1] = True

        # Calculate transition probabilities and rewards
        self.P = {}
        for s in range(self.nS):
            position = np.unravel_index(s, self.shape)
            self.P[s] = {a: [] for a in range(self.nA)}
            self.P[s][UP] = self._calculate_transition_prob(position, [-1, 0])
            self.P[s][RIGHT] = self._calculate_transition_prob(position, [0, 1])
            self.P[s][DOWN] = self._calculate_transition_prob(position, [1, 0])
            self.P[s][LEFT] = self._calculate_transition_prob(position, [0, -1])

        # Calculate initial state distribution
        # We always start in state (3, 0)
        self.initial_state_distrib = np.zeros(self.nS)
        self.initial_state_distrib[self.start_state_index] = 1.0

        self.observation_space = spaces.Discrete(self.nS)
        self.action_space = spaces.Discrete(self.nA)

        self.render_mode = render_mode

        # pygame utils
        self.cell_size = (60, 60)
        self.window_size = (
            self.shape[1] * self.cell_size[1],
            self.shape[0] * self.cell_size[0],
        )
        self.window_surface = None
        self.clock = None
        self.elf_images = None
        self.start_img = None
        self.goal_img = None
        self.cliff_img = None
        self.mountain_bg_img = None
        self.near_cliff_img = None
        self.tree_img = None