Question

I want to simulate stock paths. I have simulated 1000 paths with 22 trading days (1 starting value). Now I want to include it into my presentation, but animated, so I need the png files.

I want to create 1000 png files, starting with the first stock path, then the second and so on.

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:

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()
}

Here is the problem, that each additional part disappears when the loop gets to the next value, so I tried:

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()
}

(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.

The matrix has 1000 columns and 23 row entries, this should be 1000 simulations of stock pathes for 22 trading days.

How can I change that the error does not appear anymore? Thanks!

Answer 1

Use two for loops. The outer loop will create each png/jpeg. The inner one will build up each individual plot.

for(i in 1:1000) {
  jpeg(paste("1000s", i, ".png", sep=""))
  plot(0, 0, xlim=c(1,23), ylim=c(17,24), xlab="", ylab="")

  for(j in 1:i) {
    lines(c(1:23), matrix[, j], col=j)
  } 
  dev.off()
}