(This article was first published on

**Guy Abel » R**, and kindly contributed to R-bloggers)I was trying to create some sequential plots today in R to analyse some MCMC simulations. I found the par(ask=TRUE) command very useful for looking at iterations of individual parameter values. Setting the ask graphical parameter to TRUE (before a for loop) allows you to update plots by clicking on the plotting device (in windows). Here is some example code to show how par(ask=TRUE) works.

xx <- rnorm(1000) xx <- matrix(xx,10,100) par(ask = TRUE) plot(xx[1,], type="n", ylim=range(xx), ylab="") for(i in 1:10){ plot(xx[i,], ylim=range(xx), ylab="", type="l") }

This will give the following output after each click:

If you want to keep previous plotted lines on the plot you can adapt the for loop in such a manner:

par(ask=TRUE) plot(xx[1,], type="n", ylim=range(xx), ylab="") for(i in 1:10){ plot(xx[1,], ylim=range(xx), ylab="", type="l") for(j in 1:i){ lines(xx[j,]) } }

This will give the following output after each click:

To

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