r - Adjusting figure margins in Rmarkdown

Question

I am trying to adjust the piechart figure in my Rmarkdown document so that it spans the width of the page or at least becomes wide enough to fit all of the labels.

I have tried everything - adjusting figure.height and figure.width, margins with par(mar) and par(oma), but nothing seems to work. Either the pies themselves become smaller, or the labels are even more cut off. I would like the pies to be as large as possible with clearly visible labels, but every time it renders small pies and tiny labels.

Is there a workaround at least so that labels are not cut off (or can overlap the adjacent chart)? Any suggestions would be appreciated.

```{r, figure.align = "center", figure.height = 10, figure.width = 12}

par(mfrow=c(1,3), cex.axis=1.5, cex.lab=1.5) 
par(mar = c(4,2,4,2))
par(oma = c(3, 3, 3, 3))
pie(a, labels = lbls,  font = 2, col = c("tomato", "white"), cex=2)
pie(b, lbls2, font = 2, col = c("tomato", "white"), cex=2) 
mtext(side=3, text="Plan Breakdown: Top 20% of Users")
pie(c, lbls3,  font = 2, col = c("tomato", "white"))

Answer 1

Your figure size is constrained by the document margins unless you specify an out.width. If your figure width is larger than the margins of the page, then R Markdown/knitr will create a figure of the specified aspect ratio but shrink it down to fit within the margins.

To solve this, use out.width to set the width and height of the plot in the pdf. Something like:

```{r, fig.align = "center", fig.height = 8, fig.width = 8,
    out.width = "8.5in"}

pie(a, labels = lbls,  font = 2, col = c("tomato", "white"), cex=2)
pie(b, lbls2, font = 2, col = c("tomato", "white"), cex=2) 
mtext(side=3, text="Plan Breakdown: Top 20% of Users")
pie(c, lbls3,  font = 2, col = c("tomato", "white"))
````

See this page on knitr chunk options for more information.