This is a simple Rmd file that demonstrates how DataPackageR processes Rmarkdown files and creates data sets that are then stored in an R data package.

In the config.yml for this example, this file is listed first, and therefore processed first.

This particular document simply subsets the cars data set:

summary(cars)
##      speed           dist       
##  Min.   : 4.0   Min.   :  2.00  
##  1st Qu.:12.0   1st Qu.: 26.00  
##  Median :15.0   Median : 36.00  
##  Mean   :15.4   Mean   : 42.98  
##  3rd Qu.:19.0   3rd Qu.: 56.00  
##  Max.   :25.0   Max.   :120.00
dim(cars)
## [1] 50  2

cars consists of a data frame of 50 rows and two columns. The ?cars documentation specifies that it consists of speed and stopping distances of cars.

Let’s say, for some reason, we are only interested in the stopping distances of cars traveling greater than 20 miles per hour.

cars_over_20 = subset(cars, speed > 20)

The data frame cars_over_20 now holds this information.

Storing data set objects and making making accessible to other processing scripts.

When DataPackageR processes this file, it creates this cars_over_20 object. After processing the file it does several things:

  1. It compares the objects in the rmarkdown render environment of subsetCars.Rmd against the objects listed in the config.yml file objects property.
  2. It finds cars_over_20 is listed there, so it stores it in a new environment.
  3. That environment is passed to subsequent R and Rmd files. Specifically when the extra.rmd file is processed, it has access to an environment object that holds all the objects (defined in the yaml config) that have already been created and processed. This environment is passed into subsequent scripts at the render() call.

All of the above is done automatically. The user only needs to list the objects to be stored and passed to other scripts in the config.yml file.

The datapackager_object_read() API can be used to retrieve these objects from the environment.

Storing objects in the data package

In addition to passing around an environment to subsequent scripts, the cars_over_20 object is stored in the data package /data directory as an rda file.

Note that this is all done automatically. The user does not need to explicitly save anything, they only need to list the objects to be store in the config.yml.

This object is then accessible in the resulting package via the data() API, and its documentation is accessible via ?cars_over_20.

Data object documentation

The documentation for the cars_over_20 object is created in a subsetCars.R file in the /R directory of the data package.

While the data object document stub is created automatically, it must be edited by the user to provide additional details about the data object.