Passing graphical parameters across chunks in knitr

Question

Can anyone help me in relation to passing (or setting global) par graphical parameters across chunks in knitr.

I have a large piece of R code with a loop that generates a plot at each iteration of the loop and prints each plot on the same page of a PDF (via par(mfrow=c(5,4)).

If I break up my code into knitr chunks to make it more manageable, the graphical parameters are lost each time I leave the chunk and I lose the ability to output several plots on the same PDF page.

Is there a way to pass graphical parameters across chunks or to set the parameters as global so that all chunks can access them.

Answer 1

You can set the global.par knitr-option to TRUE like this:

```{r setup, include=FALSE}
opts_knit$set(global.par = TRUE)
```

Then set par in the next chunk and plot something:

```{r}
par(mfrow=c(5,4))
plot(something)
```

The same par-options will now be passed to the following chunks (until changed again).