Blog post: Printing R Markdown output to png files

Steve Simon

2020-01-29

Categories: Blog post Tags: R software

I have been using a tedious process to convert parts of the output of an R Markdown file to png files. I want to use png files because they can be inserted easily into a PowerPoint presentation. There’s a trick to make this work.

First, you need to adjust the paper size, as the fonts are too small in a png image of a full 8.5 by 11 inch page (or a full A4 page for those of you not in the United States).

There’s an option to control paper size of a PDF output, but you have to dig a bit to find it. Start at the section 3.3.5 of Yihui’s book on Rmarkdown. That gives you the helpful hint of geometry in the yaml header, but it only shows you how to control margins. Yihui suggests that you consult the Pandoc manual for the full list.

The Pandoc manual is huge, but look for the section “Variables for LaTeX” buried deep in the Templates section to find out more.

It offers a bit of help, but you have to link to another page, the geometry package, which is part of CTAN, the Comprehensive TeX Archive Network. click on the documentation link and nose around a bit. You have to put two and two together yourself, but here is what I added to the yaml header to get reasonable sizes.

geometry: a6paper, landscape, margins=0.25in

Now to convert from pdf to png, I use a program called ImagePrinter Pro. It’s not free, but it is professionally done and has some extra features I may end up using, such as cropping PDF files. There are free alternatives: just google for something like “convert pdf to png.”

Important notice, January 23, 2020.

I am in the process of updating my website and blog and am adopting a simpler approach that will ease the maintenance of these web pages. I have about 2,000 pages and they are in a wide range of styles and formats. I will be using markdown code to create fairly minimimally formatted html pages. The process is tricky, and I expect to see a lot of misformatted pages and broken links during this transition. Please be patient.