R Quick Tip: parameter re-use within rmarkdown YAML

May 8, 2017

(This article was first published on R – Locke Data, and kindly contributed to R-bloggers)

Ever wondered how to make an rmarkdown title dynamic? Maybe, wanted to use a parameter in multiple locations? Maybe wanted to pass through a publication date? Advanced use of YAML headers can help!

Normally, when we write rmarkdown, we might use something like the basic YAML header that the rmarkdown template gives us.

title: "My report"
date: "18th April, 2017"
output: pdf_document

You may already know the trick about making the date dynamic to whatever date the report gets rendered on by using the inline R execution mode of rmarkdown to insert a value.

title: "My report"
date: "`r Sys.Date()`"
output: pdf_document

What you may not already know is that YAML fields get evaluated sequentially so you can use a value created further up in the params section, to use it later in the block.

  dynamictitle: "My report"
  reportdate: !r Sys.Date()
output: pdf_document
title: "`r params$dynamictitle`"
date: "`r params$reportdate`"

By doing this, you can then pass parameter values into the render() function when you want to generate a report.


Parameter re-use within rmarkdown enables you to dynamically generate vital metadata for the report and use values in multiple places within the document. Very handy!

The post R Quick Tip: parameter re-use within rmarkdown YAML appeared first on Locke Data. Locke Data are a data science consultancy aimed at helping organisations get ready and get started with data science.

To leave a comment for the author, please follow the link and comment on their blog: R – Locke Data.

R-bloggers.com offers daily e-mail updates about R news and tutorials on topics such as: Data science, Big Data, R jobs, visualization (ggplot2, Boxplots, maps, animation), programming (RStudio, Sweave, LaTeX, SQL, Eclipse, git, hadoop, Web Scraping) statistics (regression, PCA, time series, trading) and more...

If you got this far, why not subscribe for updates from the site? Choose your flavor: e-mail, twitter, RSS, or facebook...

Comments are closed.

Search R-bloggers


Never miss an update!
Subscribe to R-bloggers to receive
e-mails with the latest R posts.
(You will not see this message again.)

Click here to close (This popup will not appear again)