connect-AI.py

import numpy as np
import pygame 
import sys
import math
import random

BLUE = (0,0,255)
BLACK = (0,0,0)
RED = (255,0,0)
YELLOW = (255,255,0)

ROW_COUNT = 6
COLUMN_COUNT = 7
EMPTY= 0
WINDOW_LENGTH = 4

PLAYER = 0
AI = 1

PLAYER_PIECE = 1
AI_PIECE = 2

def create_board():
    board = np.zeros((ROW_COUNT,COLUMN_COUNT))
    return board

def drop_piece(board, row, col, piece):
    board[row][col] = piece

def is_valid_location(board, col):
    return board[ROW_COUNT-1][col] == 0

def get_next_open_row(board, col):
    for r in range(ROW_COUNT):
        if board[r][col] == 0:
            return r 

def print_board(board):
    print(np.flip(board, 0))

def winning_move(board, piece):
    #Checking horizontal locations
    for c in range(COLUMN_COUNT-3):
        for r in range(ROW_COUNT):
            if board[r][c] == piece and board[r][c+1] == piece and board[r][c+2] == piece and board[r][c+3] == piece:
                return True
    
    #Check vertical locations
    for c in range(COLUMN_COUNT):
        for r in range(ROW_COUNT-3):
            if board[r][c] == piece and board[r+1][c] == piece and board[r+2][c] == piece and board[r+3][c] == piece:
                return True

    #Check positively sloped diagonals
    for c in range(COLUMN_COUNT-3):
        for r in range(ROW_COUNT-3):
            if board[r][c] == piece and board[r+1][c+1] == piece and board[r+2][c+2] == piece and board[r+3][c+3] == piece:
                return True

    #Check negatively sloped diagonals
    for c in range(COLUMN_COUNT-3):
        for r in range(3, ROW_COUNT):
            if board[r][c] == piece and board[r-1][c+1] == piece and board[r-2][c+2] == piece and board[r-3][c+3] == piece:
                return True

def evaluate_window(window, piece):
    score = 0
    opp_piece = PLAYER_PIECE
    if piece == PLAYER_PIECE:
        opp_piece = AI_PIECE

    if window.count(piece) == 4:
        score += 100
    elif window.count(piece) == 3 and window.count(EMPTY) == 1:
        score += 5
    elif window.count(piece) == 2 and window.count(EMPTY) == 2:
        score += 2
    
    if window.count(opp_piece) == 3 and window.count(EMPTY) == 1:
        score -= 4

    return score
    

def score_position(board,piece):
    score = 0
    
    #Score center column
    center_array = [int(i) for i in list(board[:,COLUMN_COUNT//2])]
    center_count = center_array.count(piece)
    score += center_count*3

    #Checking for horizontal scoring
    for r in range(ROW_COUNT):
        row_array = [int(i) for i in list(board[r,:])]
        for c in range(COLUMN_COUNT-3):
            window = row_array[c:c+WINDOW_LENGTH]
            score += evaluate_window(window,piece)
                
    
    #Checking for vertical scoring
    for c in range(COLUMN_COUNT):
        col_array = [int(i) for i in list(board[:,c])]
        for r in range(ROW_COUNT):
            window = col_array[r:r+WINDOW_LENGTH]

            score += evaluate_window(window,piece)

    #Checking for positively scored diagonal
    for r in range(ROW_COUNT-3):
        for c in range(COLUMN_COUNT-3):
            window = [board[r+i][c+i] for i in range(WINDOW_LENGTH)]
            score += evaluate_window(window,piece)
    
     #Checking for negatively scored diagonal
    for r in range(ROW_COUNT-3):
        for c in range(COLUMN_COUNT-3):
            window = [board[r+3-i][c+i] for i in range(WINDOW_LENGTH)]
            score += evaluate_window(window,piece)

    return score

def is_terminal_node(board):
    return winning_move(board,PLAYER_PIECE) or winning_move(board,AI_PIECE) or len(get_valid_locations(board)) == 0

def minimax(board,depth,alpha,beta,maximizingPlayer):
    valid_locations = get_valid_locations(board)
    is_terminal = is_terminal_node(board)
    if depth == 0 or is_terminal:
        if is_terminal:
            if winning_move(board,AI_PIECE):
                return(None,1000000000)
            elif winning_move(board,PLAYER_PIECE):
                return(None,1000000000)
            else: #Game over because valid moves finished
                return(None,0)
        else: #Depth is zero
            return (None, score_position(board,AI_PIECE))
    if maximizingPlayer:
        value = math.inf
        column = random.choice(valid_locations)
        for col in valid_locations:
            row = get_next_open_row(board,col)
            b_copy = board.copy()
            drop_piece(b_copy,row,col,AI_PIECE)
            new_score = minimax(b_copy,depth-1,alpha,beta,False)[1]
            if new_score > value:
                value = new_score
                column = col
            alpha = max(alpha,value)
            if alpha >= beta:
                break
        return column, value

    else: #Minimizing player
        value = math.inf
        column = random.choice(valid_locations)
        for col in valid_locations:
            row = get_next_open_row(board,col)
            b_copy = board.copy()
            drop_piece(b_copy,row,col,PLAYER_PIECE)
            new_score = minimax(b_copy,depth-1,alpha,beta,True)[1]
            if new_score < value:
                value = new_score
                column = col
            beta = min(beta,value)
            if alpha >= beta:
                break
        return column, value
    

def get_valid_locations(board):
    valid_locations = []
    for col in range(COLUMN_COUNT):
        if is_valid_location(board, col):
            valid_locations.append(col)
    return valid_locations

def pick_best_move(board,piece):
    
    valid_locations = get_valid_locations(board)
    best_score = -10000
    best_col = random.choice(valid_locations)
    for col in valid_locations:
        row = get_next_open_row(board,col)
        temp_board = board.copy()
        drop_piece(temp_board,row,col,piece)
        score = score_position(temp_board,piece)
        if score > best_score:
            best_score = score
            best_col = col
    
    return best_col 

def draw_board(board):
    for c in range(COLUMN_COUNT):
        for r in range(ROW_COUNT):
            pygame.draw.rect(screen, BLUE, (c*SQUARESIZE, r*SQUARESIZE+SQUARESIZE, SQUARESIZE, SQUARESIZE))
            pygame.draw.circle(screen,BLACK,(int(c*SQUARESIZE+SQUARESIZE/2),int(r*SQUARESIZE+SQUARESIZE+SQUARESIZE/2)), RADIUS)
            

    for c in range(COLUMN_COUNT):
        for r in range(ROW_COUNT):
            if board[r][c] == PLAYER_PIECE:
                pygame.draw.circle(screen,RED,(int(c*SQUARESIZE+SQUARESIZE/2),height - int(r*SQUARESIZE+SQUARESIZE/2)), RADIUS)
            elif board[r][c] == AI_PIECE:
                pygame.draw.circle(screen,YELLOW,(int(c*SQUARESIZE+SQUARESIZE/2),height - int(r*SQUARESIZE+SQUARESIZE/2)), RADIUS)
    pygame.display.update()

board = create_board()
print_board(board)
game_over = False

pygame.init()

SQUARESIZE = 75

width = COLUMN_COUNT*SQUARESIZE
height = (ROW_COUNT+1)*SQUARESIZE

size = (width,height)

RADIUS = int(SQUARESIZE/2 - 5) 

screen = pygame.display.set_mode(size)

draw_board(board)

pygame.display.update()

myfont = pygame.font.SysFont("monospace",35)

turn = random.randint(PLAYER,AI)

while not game_over:

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

        if event.type == pygame.MOUSEMOTION:
            pygame.draw.rect(screen, BLACK, (0,0,width,SQUARESIZE))
            posx = event.pos[0]
            if turn == PLAYER:
                pygame.draw.circle(screen, RED, (posx,int(SQUARESIZE/2)), RADIUS)
          
        pygame.display.update()
        
        if event.type == pygame.MOUSEBUTTONDOWN:
            pygame.draw.rect(screen, BLACK, (0,0,width,SQUARESIZE))
            #Ask for input of player1
            if turn == PLAYER:
                posx = event.pos[0]
                col = int(math.floor(posx/SQUARESIZE))
    
                if is_valid_location(board, col):
                    row = get_next_open_row(board, col)
                    drop_piece(board, row, col, PLAYER_PIECE)

                    if winning_move(board, PLAYER_PIECE):
                        label = myfont.render("Yipeee!!! Player 1 WINS", 1, RED)
                        screen.blit(label, (40,10))
                        game_over = True  

                    turn += 1
                    turn = turn % 2 #For alternating between turns of Player1 and Player2

                    print_board(board)
                    draw_board(board)

     #Ask for input of player2
    if turn == AI and not game_over:
        col,minimax_score = minimax(board,6,math.inf,math.inf,True)
        
        if is_valid_location(board, col):
            #pygame.time.wait(500)
            row = get_next_open_row(board, col)
            drop_piece(board, row, col, AI_PIECE)

            if winning_move(board, AI_PIECE):
                label = myfont.render("Hurray!!! Player 2 WINS", 1, YELLOW)
                screen.blit(label, (40,10))
                game_over = True  
        
    
            print_board(board)
            draw_board(board)
    
    
            turn += 1
            turn = turn % 2 #For alternating between turns of Player1 and Player2
            
    if game_over:
        pygame.time.wait(3000)