Swirl 1.2

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Del curso dictado por Johns Hopkins University

Developing Data Products

1338 calificaciones

Johns Hopkins University

Developing Data Products

1338 calificaciones

Curso 9 de 10 en SpecializationData Science

A data product is the production output from a statistical analysis. Data products automate complex analysis tasks or use technology to expand the utility of a data informed model, algorithm or inference. This course covers the basics of creating data products using Shiny, R packages, and interactive graphics. The course will focus on the statistical fundamentals of creating a data product that can be used to tell a story about data to a mass audience.

De la lección

Swirl and Course Project

Week 4 is all about the Course Project, producing a Shiny Application and reproducible pitch.

Conoce a los instructores

Brian Caffo, PhD
Professor, Biostatistics
Bloomberg School of Public Health
Jeff Leek, PhD
Associate Professor, Biostatistics
Bloomberg School of Public Health
Roger D. Peng, PhD
Associate Professor, Biostatistics
Bloomberg School of Public Health

Now I'll show you how you can write your own swirl courses and lessons.

In order to do that, you're going to need a package call swirlify,

which I'll load up right now.

All right,

so swirlify is always aware of your current working directory.

My working directory right now is just my home folder, so

I'm going to set my directory.

I have a special directory on my desktop called

Courses where I like to keep some of my swirl courses and develop them.

So you can start writing a new swirl course and

a new lesson with the new lesson function.

I'm going to name this lesson one and

I'll name the course My First Course.

All right, so executing that function did several things.

The first thing that it does is that it opens up this YAML file.

All swirl lessons are written in YAML.

YAML is a fairly easy to understand markup language.

The way that swirl uses it is in this way where each question

is demarcated by a hyphen, and then there is a set of key

value pairs that specifies each type of question, and

what goes into that question in your swirl lesson.

So just to show you, just to sort of give you a look,

let's go to My Courses folder.

So, this is the course I just created, called My First Course.

Opening it up there is one lesson inside of it, called Lesson_1.

Each course is its own folder and

each lesson is its own folder inside of a course.

And then that new lesson function created a couple files.

The first file, customTests.R is where you can specify your own functions for

testing the correctness of swirl questions.

We'll talk about answer testing a little bit later.

Dependson.txt is a text file that you can use to list

the names of functions, excuse me, the names of R packages that are on Cram.

That's where we'll check to make sure R installed before the lesson begins.

initLesson.R is an R script, and

whatever you write in that R script will happen before a lesson starts,

so you can load the data inside of initLesson.R or

you can create functions that will soon then be used in the lesson.

And then this lesson.yaml file is exactly what we're looking at here

inside of RStudio.

I like using RStudio for writing swirl lessons because having a text editor and

an R console next to each other on the same screen works for me.

I certainly recommend using RStudio but

different people have their different work flows.

So I have this new lesson all set up.

Now I want to start adding questions.

So you can use the wq series of functions that come with swirl find.

And as you can see, there's several

different kinds of questions that you can include in a lesson.

The most simple kind of question that you can include is what's called

a message question.

So I'm just going to execute this wq message function and

go over to my lesson.yaml file, and

as you can see, it's added the template for a message question.

So I'm going to edit this message question and say, Welcome to lesson 1!

And then that's all I need to do in order to write a simple message question.

I'm then going to add another question, this time a command question.

So a command question will prompt the student

to actually enter some R code into the R console.

And as you can see, the question template is added to the lesson.yaml file.

So I'm going to ask a student a simple question like

add 2 and 2 using the plus operator.

And then the CorrectAnswer is just the very simple R expression of 2 + 2.

And then this AnswerTests is a function

that tests the correctness of what the student enters into the console.

Omnitest is a function that comes packaged in swirl and for

80-90% of the questions you're going to be asking, you want to use Omnitest.

So in this case I'm just going to write 2 + 2 inside of this

CorrectExpression argument, and then I'm going to give

a very simple hint to the user and say Just type 2 + 2.

All right, so I've written some questions, now time to start testing this lesson.

Whenever I add a lesson to a course,

you should add it to what's called the course manifest.

You can do this very easily by using the add_to_manifest function.

And just to show you what that did is that created this manifest file.

This is so we're inside of the course directory right now.

That is the course which is my first course.

And this manifest file just

keeps track of the order that you want your lessons to be displayed in.

And it also keeps track of what the lessons in the course are.

That way if you want to put data or other files inside of this course folder,

you can do that and those files won't show up

as a lesson that the student can select when they're going,

when they're choosing a lesson to work on inside of swirl.

So this manifest file just kind of keeps things organized.

So I've added this lesson to the manifest.

Now I'm, now let's test out this lesson.

So just to check the general formatting of this lesson,

I'm going to use the test lesson function.

If I didn't get any warnings or any messages, that means that

this lesson passed some formatting checks that come with swirlify.

Then I want to actually use this lesson inside of swirl, so

I'm going to use the demo lesson function.

And as you can see, that takes us right into the lesson that we're writing.

And I don't need to go through swirl's menu,

so Welcome to lesson 1 is the first question.

Add 2 and 2 using a plus operator.

I'll do that.

And then that's the end of the lesson.

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