Passing Parameters to R Markdown

Question

I am trying to create a parameterized report in R Markdown based on the following tutorial: http://rmarkdown.rstudio.com/developer_parameterized_reports.html#passing-parameters

I'm trying to pass a file path as a parameter from the r console using render. Like this:

render('rmarkdownfile.rmd',params= list( client= "clientdata.csv"))

and my markdown file looks like this:

title: "Liquidity Report"
output: pdf_document
params: client:"clientdata.csv"
---
```{r plot, echo=FALSE, warning=FALSE}
cftest <- read.csv(params$client)

But I get an error that says:

Eror in read.table(file=file, header=header, sep=sep, quote=quote, : 'file' must be a character string or connection Calls:

It seems like Markdown is not recognizing the parameters even though I'm following the steps of the tutorial. Has anyone been able to successfully use parameters in R Markdown?

Also, I'm following the recommendations of the tutorial and am using the R Studio preview as well as the latest builds of r markdown and knitr.

Thank you for the help!

Rafael

Answer 1

What I like to do is not just specify a file name but also a directory on my parameterized reports.

---
title: Liquidity Report
date: '`r strftime(Sys.time(), format = "%B %d, %Y")`'
output:
  pdf_document:
    number_sections: yes
    theme: cerulean
    toc: yes
    toc_depth: 2
params:
  directory:
    value: x
  file:
    value: x
---

```{r, include = FALSE}
knitr::opts_chunk$set(
      echo    = FALSE
    , warning = FALSE
    , message = FALSE
)

## Pull in the data
dataset <- read.csv(file.path(params$directory, params$file))
```

And then in your render function you can:

rmarkdown::render(
      input  = 'LiquidityReport.Rmd'
    , params = list(
          directory = '~/path/to/data'
        , file      = 'clientdata.csv'
        )
)

The knitr docs can add more information: > ?knitr::knit_params

Answer 2

In my case it worked, just had to change the indentation in the header and some names which are available in my folder...

Here my jnk.Rmd

---
title: "Liquidity Report"
output: pdf_document
params: 
  client: "NAMESPACE"
---
```{r plot, echo=FALSE, warning=FALSE}
cftest <- read.csv(params$client)
```

And this is what I called in the console : render('jnk.Rmd',params= list( client= "NAMESPACE"))