Function to get the segments (walls) of cells ready for plotting

createXYWalls.R

#plotting
createXYWalls <- function (cells) {
  #let each cell start at its XY position
  xs<- NULL; ys<-NULL; xe <- NULL; ye<-NULL
  for (i in 1:nrow(cells)) {
    if(cells$W[i])
    {
      xs <- c(xs, cells$x[i]+1)   
      ys <- c(ys, cells$y[i]+0)   
      xe <- c(xe, cells$x[i]+1)   
      ye <- c(ye, cells$y[i]+1)         
    }
    if(cells$E[i])
    {
      xs <- c(xs, cells$x[i]+0)   
      ys <- c(ys, cells$y[i]+0)   
      xe <- c(xe, cells$x[i]+0)   
      ye <- c(ye, cells$y[i]+1)         
    }
    if(cells$N[i])
    {
      xs <- c(xs, cells$x[i]+0)   
      ys <- c(ys, cells$y[i]+0)   
      xe <- c(xe, cells$x[i]+1)   
      ye <- c(ye, cells$y[i]+0)         
    }
    if(cells$S[i])
    {
      xs <- c(xs, cells$x[i]+0)   
      ys <- c(ys, cells$y[i]+1)   
      xe <- c(xe, cells$x[i]+1)   
      ye <- c(ye, cells$y[i]+1)         
    }
    
  }
  walls <- data.frame(xs,ys,xe,ye)
  return(walls)
}