README.md

In Swarchal/fridayDemo:

Example Repository

Good practises in R

Repo used for Friday demonstration.

Very important

Pretty useful

testthat

Creating your package

There are a few ways to do this, the easiest is using devtools

# change working directory to where you want the package
setwd('~/my_folder')
devtools::create('myNewPackage')

This will create a folder called myNewPackage that contains everything you need to start an R package.

Create test folder with devtools

devtools::use_testthat()

This creates a folder within your package to store tests, and sets up the infrastructure for you.

Write your function, and document with Roxygen

#' Times a number by ten
#'
#' Given a number, this will times a number by 10. This also works with vectors.
#'
#' @param x number of vector of numbers
#' @return out output, which is input times ten
#' @export # writes to NAMESPACE for you
#' @examples
#' times_ten(10)

times_ten <- function(x){
    return(x * 10)
}

The bit at the top prefixed by #' lets you document your code within the source, and Roxygen will create the man documents automatically. Alternatively you can write the documentation separately but it's a huge pain.

Create docs automatically

devtools::document()

This writes the man pages for you, from all the #' in your code.

Write tests for your code

The tests go in the tests/testthat folder, and the files have to begin with test.

An example of a test for the times_ten() function would be in a file called tests/testthat/test_times_ten.R and contains:

context("test times_ten")

test_that("times_ten works as expected",{
    expect_error(times_ten("string"))
    expect_error(times_ten())
    expect_output(times_ten(10), 100)
    expect_output(times_ten(-1), -10)
})

To test all the code in your package that you have writen tests for, the easiest way is ctrl + shift + t while in RStudio.

You can test the entire build of your package, using devtools::check(). This will not only run any tests you have written, but check your package is properly documented and built.

Putting your package on github

If you have all your functions in a package, it's worthwhile putting it on github. Github allows you to install your package from any computer, and also lets you track any changes you have made to your code over time, giving you a complete history of whatever you have changed -- very useful if you break anything.

Create a repo on github

Get a github account and create an empty repo. The best option is to name is whatever you named your package folder, in this case myNewPackage.

Setting up git

You're in the deep end here.

• Get git and set up a username and email with:

git config --global user.name 'JoeBloggs'
git config --global user.email '[e-mail]'

Use the same email address and user-name as you signed up to github with to make things easier.

Initialise git in your package folder

cd ~/myNewPackage
git init

Add all your files to push to github

git add .
git commit -m "my first commit"

Tell git where to push the files to (your Github repository you just made)

git remote add origin https://github.com/JoeBloggs/myNewPackage.git

Push all your files to github

git push -u origin master

Then check github.com to see if your files are there.

Adding changes to your package

Say you made some changes to your code, to add that to your github repository:

git add updated_function.R      # or whatever the file you want to add is called
git commit -m "made this function better"
git push origin master

Getting your package from github

devtools::install_github('JoeBlogs/myNewPackage')

Automated testing

It's possible to automatically test your code/package every time you push any changes to github.

For this I use travis-ci, which requires you do add a .travis.yml file to your package. Then every time your package changes travis will check the package still builds, run any tests you wrote with testthat and send you an email if you broke anything.

You can also check how well you have tested your code with codecov.

Swarchal/fridayDemo documentation built on May 9, 2019, 3:25 p.m.