title: Plot multiple graphs on one plot in R within loop
body: <p>I want to plot some curves in one plot in a for loop in R and save it as a png.
  When I do this with par(new=False) the axis get bold, because it is rendered for every of the curves, so I turn off the axis for every but the first plot, but this seems like a very inelegant solution.</p>
  
  <p>What would be a more R-like way to do so?
  Here is all of my code until now:</p>
  
  <pre><code>x&lt;-matrix(rnorm(20000,5,3), nrow=200, ncol=100)
  y&lt;-matrix(0, nrow=200, ncol=100)
  
  for (i in 1:200) {
    for (j in 1:100) {
      y[i,j] &lt;- mean(x[i,1:j])
    } 
  }
  
  png(filename="./a1.png")
  
  #here is the ugly bit
  plot(1:100,y[1,1:100],type="l", ylim=range(c(10,0)))
  par(new = TRUE)
  for (j in 2:200) {
    plot(1:100,y[j,1:100],type="l", ylim=range(c(10,0)), xaxt='n', yaxt='n', ann=FALSE)
    par(new = TRUE)
  }
  
  graphics.off()
  </code></pre>