playNums.r

#' Play sliding puzzles
#' @author Taiyun Wei
#' @param size vector, the size of puzzle
#' @param bg, the color of number-cases
#' @param z, the puzzle matrix, can be generated automaticly
playNums <- function(size = c(4,4), bg = "lightblue",z = NULL, ...) {
n <- size[1]
m <- size[2]
z.right <- matrix(1:(n*m), n, byrow = TRUE)
z.right[n,m]<- 0

##calculate inverse number
neg_seq.length <- function(x){
len <- 0
for(i in 1:(length(x) - 1)){
tmp <- x[(i+1):length(x)] - x[i]
len <- len + sum(tmp < 0)
}
}

len.right <- neg_seq.length(as.vector(z.right)) +n+m


    if (is.null(z))
        z <- matrix(sample(0:(n*m - 1)), n)
    len.z <- neg_seq.length(as.vector(z)) + sum(which(z==0, arr.ind = TRUE))


    ####guarantee the game can be solved
    while((len.right%%2)!=(len.z%%2)){
    z <- matrix(sample(0:(n*m - 1)), n)
    len.z <- neg_seq.length(as.vector(z)) + sum(which(z==0, arr.ind = TRUE))
    }
    z[!z]<-NA


    ##plot puzzles
    replot <- function(z) {
        bg <- ifelse(z, bg, "white")
        fg <- ifelse(z, bg, "white")
        par(mar = c(0, 0, 0, 0), bg = "white")
        plot(c(0, m), c(0, n), type = "n",axes = FALSE, asp = 1, xlab = "",
            ylab = "")
        segments(0:m, rep(0, m + 1), 0:m, rep(n, m + 1), col = "grey",
            lwd = 2)
        segments(rep(0, n + 1), 0:n, rep(m, n + 1), 0:n, col = "grey",
            lwd = 2)
        symbols(0.5 + rep(0:(m - 1), each = n), 0.5 + rep((n -
            1):0, m), squares = rep(0.9, n*m), add = TRUE, inches = FALSE,
            fg = as.vector(fg), bg = as.vector(bg))
        text(0.5 + rep(0:(m - 1), each = n), 0.5 + rep((n -
            1):0, m), as.vector(z), cex = 3)
    }

    ##push function
    push <- function(x, begin, space) {
        tmp <- x[space]
        if (begin < space) {
            x[(begin + 1):space] <- x[begin:(space - 1)]
            x[begin] <- tmp
        }
        if (begin > space) {
            x[(begin - 1):space] <- x[begin:(space + 1)]
            x[begin] <- tmp
        }
        x
    }

    count <- 0
    mousedown <- function(buttons, x, y) {
    plx <- grconvertX(x, "ndc", "user")
        ply <- grconvertY(y, "ndc", "user")
        m.col <- ceiling(plx)
        m.row <- n - floor(ply)
        ind.NA <- which(is.na(z), arr.ind = TRUE)
        if (!xor(m.row == ind.NA[1], m.col == ind.NA[2]))
            cat("Warning: Cannot push any case!\n")

        ##row push
        ind.NA <- which(is.na(z), arr.ind = TRUE)
        if (ind.NA[1] == m.row & ind.NA[2] != m.col) {
            z[m.row, ] <<- push(z[m.row, ], m.col, ind.NA[2])
            cat("step = ", count <<- count + 1, "\n")
        }
        ##col push
        if (ind.NA[1] != m.row & ind.NA[2] == m.col) {
            z[, m.col] <<- push(z[, m.col], m.row, ind.NA[1])
            cat("step = ", count <<- count + 1, "\n")
        }
        replot(z)
        flag <- z == z.right
        if (all(flag[!is.na(flag)])){
        "You win!"
        }
    }

    replot(z)
    getGraphicsEvent("Game begin!", onMouseDown = mousedown)

}