As you may know, I recently published a R book in amazon. I decided to keep R exercises out of the book and serve them freely over the web. This was not a difficult decision since I’m still writing and revising all questions. My experience tell me that good exercises requires time to develop and I didn’t want to rush it just for the sake of publishing the book.

I’m a big fan of package Exams and, given that I already have some questions about R in this format, I should use it to build the exercises for my book. The reader is better served than using a single version format as he/she can rebuild a different set of exercises each time, and take the same set of exercises over and over, if needed. The problem is that building a new exam in package Exams requires R and latex compilation. I could compile in my computer and provide pdf files of different versions in the website, but this is not really an elegant solution.

With that in mind, I was able to write a shiny app that distributes pdf files in the internet. I customized all templates so that they fit my needs. I have never seen anything like that, which is why I am posting it here. I’m still amazed of how much a few lines of code in Shiny can do.

The users can choose the chapter and the language. After clicking the “build” button, a custom call to exams2pdf is made and the user can download a zip file with the contents of the exercises.

Give it a try here.

Curious about the code? All files are available in github.