Connect 4

This game is a classical 2 players game called Connect 4. By turns, each player drops a token in one of the 7 columns. The player that can align 4 tokens in a row, column or diagonal wins.

This is a 2 players game of 0 sum with perfect information.

Goal

The goal of this game is to align 4 tokens in a row, column or diagonal.

Score

• The player that aligns 4 tokens:

  • 1

• The other player:

  • -1

• In case the board is full and no player aligned 4 tokens:

  • 0

Import

from IArena.games.Connect4 import Connect4Rules
from IArena.games.Connect4 import Connect4Movement
from IArena.games.Connect4 import Connect4Position

Movement

A movement is represented by an int representing the number of the column where to drop the token:

• n

  • int

  • 0 <= n < n_columns

  • Index of the column where to drop the token

movement = Connect4Movement(n=2) # Drop the token in the column 2

Position

A position is represented by a matrix defined as List[List[int]] where:

• Connect4Matrix.EMPTY_CELL = -1 - Empty cell

• 0 - Player 0 token

• 1 - Player 1 token

Constructor

The position is created by a subclass Connect4Matrix, by a matrix and a player, or by a short str matrix definition:

# Using Connect4Matrix
matrix = Connect4Matrix(
    matrix=[[-1,-1,-1], [-1,-1,-1], [-1,-1,-1], [0, 1, 0]],
    player=1)
position = Connect4Position(
    rules=Connect4Rules(),
    position=matrix)

# Using constructor
position = Connect4Position(
    rules=Connect4Rules(),
    matrix=[[-1,-1,-1], [-1,-1,-1], [-1,-1,-1], [0, 1, 0]],
    player=1)

# Using short str
position = Connect4Position.from_str('1|4|0|1|0')

Methods

The standard Connect 4 game is based on a 6x7 board that starts empty. However, this class allows any size of board. To handle this, and the rest of the position information, the Connect4Position has these methods:

• next_player() -> PlayerIndex

  • Returns the index of the next player

• get_matrix() -> List[List[int]]

  • Returns a copy of the matrix

• n_rows() -> int

  • Returns the number of rows

• n_columns() -> int

  • Returns the number of columns

Also, the class has 2 useful static methods to transform matrices. These methods helps to understand the short str matrix definition. Using them, you can convert a short str to a matrix and vice versa:

• convert_short_str_to_matrix_str(short_str: str) -> str

  • Converts a short str to a matrix str

• convert_short_str_to_matrix(short_str: str) -> List[List[int]]

  • Converts a short str to a matrix

• convert_matrix_to_short_str(matrix: List[List[int]]) -> str

  • Converts a matrix to a short str

Rules

It counts with 2 methods, apart from all the methods from IGameRules:

• n_rows() -> int

• n_columns() -> int

Constructor

Can receive 3 arguments:

• initial_player

  • int

  • {0,1}

  • Initial player

  • Default: 0

• initial_matrix

  • List[List[int]]

  • Initial matrix

  • Default: None. If None, it will create an empty matrix of 6x7

• initial_matrix_str

  • str

  • Initial matrix in short str format

  • Default: None. If None, it will create an empty matrix of 6x7

# Default 6x7 empty board
rules = coinsRules()

# Custom 4x4 empty board
rules = coinsRules(
  initial_matrix_str='0|4|||||')