title: Plotting 1000 simulations with loop, error messsage
body: <p>I want to create 1000 png files, while each file should contain one simulated stock pathes but also additional the others.</p>
  
  <p>So I start with the first path, add a second to the plot, add the third and so on, so at the end I have a plot with 1000 simulations, here is my code:</p>
  
  <pre><code>for(i in 1:1000){
  #jpeg(paste("1000s",i,".png",sep=""))
  plot(c(1:23),matrix[,1],type="l",ylim=c(17,24))
  lines(c(1:23),matrix[,i],type="l",col=i)
  #dev.off()
  }
  </code></pre>
  
  <p>Here is the problem, that each additional part disappears when the loop gets to the next value, so I tried:</p>
  
  <pre><code>plot(0,0 , xlim=c(1,23),ylim=c(17,24),xlab="",ylab="")
  for(i in 1:1000){
  jpeg(paste("1000s",i,".png",sep=""))
  lines(c(1:23),matrix[,i],type="l",col=i)
  dev.off()
  }
  </code></pre>
  
  <p>I know this is not a working example, but my problem is just a logical one with the loop, I get the following error message when I the last code: plot.new has not been called yet</p>
  
  <p>The matrix has 1000 columns and 23 row entries, this should be 1000 simulations of stock pathes for 22 trading days.</p>
  
  <p>What do I have to change? Thanks!</p>