Game of Life in R

GameOfLife.R

# Game of life.  Based on a matrix representation with cells being in either
# alive (1) or dead (0) state.

nextStep <- function(grid) {
  w = ncol(grid)
  h = nrow(grid)
  out = matrix(0,nrow=h,ncol=w)

  for (i in 1:w) {
    for (j in 1:h) {
      n = neighbours(grid,i,j)
      s = grid[i,j]
      if (s == 1 && n < 2)
         out[i,j] = 0 #under-population
      else if (s == 1 && (n == 2 || n == 3))
         out[i,j] = 1 #survices
      else if (s == 1 && n > 3)
         out[i,j] = 0 #over population
      else if (s == 0 && n == 3)
         out[i,j] = 1 # reproduction
    }
  }

  out
}

# A count of the live neighbours
neighbours <- function(g,x,y) {
  mc = max(1,x-1)
  mr = max(1,y-1)
  bc = min(x+1,ncol(g))
  br = min(y+1,nrow(g))

  # Just sum the bounds and remember to take away self!
  sum(c(g[mc:bc,mr:br])) - g[x,y]
}