Question

Write a program that will play tic-tac-toe [worth 50 pts] You will submit a SEPARATE R script.

Answer 1

1) drawing the board

draw.board <- function(board) { # Draw the board

    xo <- c("X", " ", "O") # Symbols

    par(mar = rep(0,4))

    plot.new()

    plot.window(xlim = c(0,30), ylim = c(0,30))

    abline(h = c(10, 20), col="darkgrey", lwd = 4)

    abline(v = c(10, 20), col="darkgrey", lwd = 4)

    pieces <- xo[board + 2]

    text(rep(c(5, 15, 25), 3), c(rep(25, 3), rep(15,3), rep(5, 3)), pieces, cex = 6)

    # Identify location of any three in a row

    square <- t(matrix(board, nrow = 3))

    hor <- abs(rowSums(square))

    if (any(hor == 3))

      hor <- (4 - which(hor == 3)) * 10 - 5

    else

      hor <- 0

    ver <- abs(colSums(square))

    if (any(ver == 3))

      ver <- which(ver == 3) * 10 - 5

    else

      ver <- 0

    diag1 <- sum(diag(square))

    diag2 <- sum(diag(t(apply(square, 2, rev))))

    # Draw winning lines

    if (hor > 0) lines(c(0, 30), rep(hor, 2), lwd=10, col="red")

    if (ver > 0) lines(rep(ver, 2), c(0, 30), lwd=10, col="red")

    if (abs(diag1) == 3) lines(c(2, 28), c(28, 2), lwd=10, col="red")

    if (abs(diag2) == 3) lines(c(2, 28), c(2, 28), lwd=10, col="red")

}

2) Random Tic Tac Toe

eval.winner <- function(board) { # Identify winner

    square <- t(matrix(board, nrow = 3))

    hor <- rowSums(square)

    ver <- colSums(square)

    diag1 <- sum(diag(square))

    diag2 <- sum(diag(t(apply(square, 2, rev))))

    if (3 %in% c(hor, ver, diag1, diag2)) return (1)

    else

        if (-3 %in% c(hor, ver, diag1, diag2)) return (2)

    else

        return(0)

}

# Random game

library(animation)

saveGIF ({

for (i in 1:10) {

game <- rep(0, 9) # Empty board

winner <- 0 # Define winner

player <- -1 # First player

draw.board(game)

while (0 %in% game & winner == 0) { # Keep playing until win or full board

   empty <- which(game == 0) # Define empty squares

   move <- empty[sample(length(empty), 1)] # Random move

   game[move] <- player # Change board

   draw.board(game)

   winner <- eval.winner(game) # Evaulate game

   player <- player * -1 # Change player

}

draw.board(game)

}

},

interval = 0.25, movie.name = "ttt.gif", ani.width = 600, ani.height = 600)