GitHub for Data Scientists without the terminal
In this tutorial you will learn how to get started with version control using Git and GitHub. The main goal here is to provide a step-by-step introduction to GitHub, with detailed screenshots, so that you become familiar with its main functionalities.
This tutorial is intended for grad students and academics who use
R but are unfamiliar with the command line
or terminal. I assume nothing about the computer science skills of the user, but do
assume basic knowledge of
The outline is provided below. You will learn the essential concepts and terminology of version control, Git, GitHub and GitHub desktop. This tutorial follows a learn-by-doing approach.
- Installing Git
- Signup for a GitHub account and a Hello World tutorial
- Installing GitHub Desktop
- Version control
Rcode using an example of PCA
- Create a branch, pull request and merge
- Introduction to Git functionality in RStudio
- Create and publish an
- Create an online CV
Familiarity with GitHub has become an indispensible tool for anyone working with data. Sharing code, writing software for your statistical method, producing techincal reports and creating websites have become essential skills to have in the rapidly growing field of data science. Other answers can be found here, here and here.
Each of the topics covered are separated by chapters that should be followed sequentially. Within each chapter, there are a series of steps that you need to complete. Each step starts with some instructions followed by a screenshot.
What this isn't
It is not a comprehensive tutorial of all the intracacies of Git. I skip over many fine details, because the main goal of this tutorial is an introduction to essential concepts and terminology of version control, Git, and GitHub.
It covers a variety of topics that could each be its own book. There are a plethora of online resources available for everything covered here but you can't Google something if you don't know what you're looking for in the first place.
There are several more advanced and comprehensive online resources available for learning git and github for data science oriented people including:
The main difference here is that we don't use the terminal (or command line) and provide screenshots for every step.
Chapter 1: Installing Git
Git is to GitHub, what R is to RStudio. In other words Git is the software that does all the work behind the scenes, and GitHub a user interface that makes its easier to communicate with Git (and adds functionality as well). In this chapter we will download and install Git.
Note: the screenshots provided here are from a Windows operating system, however it will be similar on a Mac or Linux.
Once the download has completed, click on the
Git-2.7.4 64-bit.exe file
.dmg on a Mac, or
.deb on Linux). Note: the version you download might be different than what I've shown here, but that's ok
Once you have read the GNU General Public License (this is not required
to continue) click on
You need to select where you want Git installed. I have chosen the default
Program Files, but you can change this if you like by clicking on
Browse... button. Once you have chosen a location click
Select the components you want to install. Ensure that at least the boxes
shown in the screenshot below have been checked. Click
This step is to select where you want the shortcut location to be stored. I
have chosen the default. Then click
Git can be used from the command line also. Selecting the second option allows you this flexibility for when you become familiar with Git. Note: you might see different options on a Mac, if you don't know which option to choose, select the default
Select the (recommended) first option and click
Note: you might see different options on a Mac, if you don't know which option to choose, select the default
Select the (recommended) first option and click
Note: you might see different options on a Mac, if you don't know which option to choose, select the default
Ensure that at least the
Enable Git Credential Manager box is checked, and click
You should see now see the following installation screen.
The following screen will appear once the Git setup has successfully completed.
Finish. Well done, you have installed Git on your system. Proceed
to Chapter 2 to signup for a GitHub account.
Chapter 2: Signup for a GitHub account and a Hello World tutorial
In this short Chapter, you will signup for a GitHub account. GitHub is like your online portfolio of code. It has a plethora of great features for creating websites, project pages and collaborating with others. Again GitHub is an interface to the version control system called Git. Other options include Bitbucket and GitLab.
Go to https://github.com/.
The longest step in this chapter is choosing your username. Think about it
carefully and ensure that its professional; it will be how you are recognized on the internet, i.e., your github website address will be github.com/username. Once you have chosen a username, enter a valid email address and password, and click on the
Sign up for GitHub button.
Choose the free plan (default) and click on the
Finish sign up button.
Well done. You now have a GitHub account. Complete the
Hello World guide
which will walk you through some functionalities of GitHub. Click on
Let's get started! button.
Complete the exercises in the Hello World tutorial and move on to Chapter 3: Installing GitHub Desktop.
Chapter 3: Installing GitHub Desktop
Traditionally, version control with Git is accessed through the command line or terminal. GitHub Desktop is a software program that makes it easier to use Git functions without having to use the command line. It also allows you to communicate with your GitHub website (github.com/username). Don't worry if the differences between Git, GitHub and GitHub Desktop are not clear to you yet. You will have a better understanding once you have completed this tutorial.
Note: in all the screenshots that follow, my username is shown, however you should be entering your username, password and email address created in Chapter 2.
Once the program has finished downloading, click on
.dmg on a Mac).
You should see this installation screen.
Once installed, open up the program and login using the GitHub username and
password you created in Chapter 2 and click on
This information is used to identify the person that made the changes to your
code. Leave the default values and click on
You should see this screen, since you haven't created any local repositories yet.
What is a repository? The purpose of Git is to manage a project, or a set of files, as they change over time. Git stores this information in a data structure called a repository (reference).
You should now be at this screen.
Click on the button in the top left corner. Your username should appear
with a list of your repositories that are currently saved in your online GitHub
account. To be able to have a local copy of this repository (by local I mean on
your computer hard drive) click on the
Clone tab and then
Clone hello-world button (I am assuming that you completed the
tutorial in Step 5 of Chapter 2).
Choose where you want to save a local copy of the
Hello World repository and click
You should now see the following contents in your GitHub desktop program.
Using your computer's file explorer (e.g. windows explorer or mac finder),
locate the local GitHub repository. If you successfully cloned your repository
you will see a
hello-world folder with a
README.md file in it, which is
the same one you created during the
Hello World exercise in Chapter 2.
Before moving on to Chapter 4, verify that the GitHub Desktop has added an
SSH key for you. An SSH key is used to establish a secure connection between
your computer and the online GitHub server. On the far top right hand side of
your online GitHub account click on the icon and navigate to
You should see one entry in the
SSH keys panel. Well done. You are now ready
to version control some
R code in Chapter 4.
Chapter 4: Version control R code using an example of PCA
In this chapter we will learn how to version control
R code using an example
of Principal Component Analysis.
Create a local (meaning on your computer) repository by clickling the
button in the top left corner of GitHub Desktop, and select the
Name the repository
pcaCars and select where you want this repository stored
on your computer. Leave the
Git ignore value at its default (we will ignore what
this is for now). Click on .
You should see the following in your GitHub Desktop. A repository called
pcaCars has been created locally on your computer, and it contains two
text files that were automatically created by the software. You can click on them
to see their contents. The most important of the two is the
This text file allows you to control what you want to version control within the
We now want to publish this repository to the remote (i.e. github.com/username). Simply click on the button in the top right hand corner. Add a description and click on .
Head over to your online github account (e.g. https://github.com/git4ds).
You should see the
pcaCars repository along with the description you entered in the
Click on the
pcaCars repository and you will see the
.gitignore files which are the same ones you have in your local repository.
Open RStudio, navigate to the
pcaCars repository and set it as your working
directory using the
Save the following code in an R script called
# cor = TRUE indicates that PCA is performed on # standardized data (mean = 0, variance = 1) pcaCars <- princomp(mtcars, cor = TRUE) # view objects stored in pcaCars names(pcaCars) # proportion of variance explained summary(pcaCars) # scree plot plot(pcaCars, type = "l")
Go back to GitHub Desktop. You will see the
pca.R file appear. Click on the
checkbox to the left of it, and you will see all the additions you have made
to the file.
On the bottom left hand side, enter a summary of the changes you have made to the repository and an (optional) description. Then click on . This is essentially telling Git to record the changes you have made and store them in a branch. We will learn about branches in Chapter 5.
You should see the following screen. You should notice that in the rectangular black box, underneath the button, a timeline. As you commit additional changes, this timeline will grow. Each circle represents a snapshot of the repository at the time of the commit. This is the power of version controlling with Git. You can see what changes you have made, and even revert back to snapshot you want.
Go to the
pcaCars repository in your online GitHub account. Do you see the
file you just created called
pca.R ? Why not? Because the commit you made was local
to your computer. In order to see these changes online, you must
push your local
changes to the
Go to GitHub Desktop and click on the button in the top right hand corner.
You should now see your local changes pushed to your online repository.
Let's make a change to the
pca.R script. Instead of a scree plot, we want
a bar plot of the variance explained for each component:
# bar plot plot(pcaCars)
Your script should now match what is shown in the screenshot below.
Go to GitHub Desktop and click on the
pca.R file. You will see that
Git automatically recognizes the changes you have made. Highlighted in red
is what has been removed from the file, and in green is what was added.
Describe the change you have made and click on
Push your local changes to the remote repository by clicking on the button. You can view the different commits you have made in GitHub Desktop by clicking on the grey circles in the timeline located in the rectangular black box.
Go to your GitHub account online to see that the changes have been updated. Click on the
History button located in to see a list of commits you have made to the repository.
History of commits you have made to the repository.
Chapter 5: Create a branch, pull request and merge
In this chapter you will learn what the words
pull request and
in the GitHub world. Branching is a much more efficient and safe alternative to
having files in a project like this:
This image (source)nicely summarises what branching is useful for:
When you have a new idea, or want to test out some existing method but don't want to modify your working script, then creating a branch is what you should do.
A branch represents an independent line of development. You can think of them as a way to request a brand new working directory (reference).
Click on the branch symbol and
name the branch
From branch entry indicates what the starting point of the
branch should be (you will see what this means shortly). Since there are no other branches
master is chosen by default. Click on .
You have now switched to the
clustering branch. Notice the second timeline
clustering underneath the
master in the black rectangular box.
You will also see a list of branches in this repository in the dropdown list next to the branch symbol . The checkmark indicates the branch you are currently on.
The motivation for creating this branch is that we want test out some code
to cluster the cars based on principal component scores. Go to RStudio and add
the following code to
pca.R and save the file. You will need to install the
ggrepel packages from CRAN
# cluster cars carsHC <- hclust(dist(pcaCars$scores), method = "ward.D2") # dendrogram plot(carsHC) # cut the dendrogram into 3 clusters carsClusters <- cutree(carsHC, k = 3) # add cluster to data frame of scores carsDf <- data.frame(pcaCars$scores, "cluster" = factor(carsClusters)) str(carsDf) # plot the first 2 PCs with cluster membership # need to install ggplot2 and ggrepel packages first # using the following command in R: # install.packages(c("ggplot2","ggrepel")) library(ggplot2) library(ggrepel) ggplot(carsDf,aes(x=Comp.1, y=Comp.2)) + geom_text_repel(aes(label = rownames(carsDf))) + theme_classic() + geom_hline(yintercept = 0, color = "gray70") + geom_vline(xintercept = 0, color = "gray70") + geom_point(aes(color = cluster), alpha = 0.55, size = 3) + xlab("PC1") + ylab("PC2") + xlim(-5, 6) + ggtitle("PCA plot of Cars")
Go to GitHub Desktop, click on the
pca.R file and you will see the changes made
have been highlighted. Describe the changes you have made and then click on
Push your local change to your online GitHub repository (i.e. the remote) by clicking on the button.
You will see the
clustering branch appear in the
Branch dropdown menu.
clustering branch and confirm that your changes to the
Switch back to the
master branch. Why isn't the clutering code there? Because
you commit your changes to the
clustering branch and not the
It should become a little more clear now what branching is and it's utility.
If you're content with the clustering results, it's time to merge the clustering code
which is sitting on the
clustering branch with the PCA code on the
This is accomplished via a
pull request. A
pull request is the first step in merging two branches.
It tells GitHub that you have committed changes to the repository and allows you to review the changes.
pull requests are a GitHub functionality and is not part of Git.
Click on the button in GitHub Desktop, enter a summary and description of the proposed changes and why you did them. Then click on .
View it on GitHub. This will open the submitted
pull request in the
pcaCars repository of your online GitHub account.
GitHub will automatically check that the merge can be completed without any conflicts. If there are no conflicts you will see the following screen. Click on .
Enter a comment about the pull request (optional) and click on .
Well done. You have successfully created a branch, submitted a pull request and
merged your changes from the
clustering branch to the
master branch. You can
clustering branch by clicking on as it is no longer needed because these changes
are now in the
Branch dropdown list you will only see the
master branch. You will
also notice that the clustering code has been merged with the PCA code.
The merge was done online. We now want to see these changes reflected on our computer (i.e. locally). To do this, go to GitHub Desktop and click on the button.
Notice that the
clustering branch still exists even though you delete it
in your online GitHub repository. Why? Because you did not delete the branch
locally (i.e. it still exists on your computer). Click on the settings dropdown menu
You will now only see the master branch in both the dropdown list and the black rectangular box.
Chapter 6: Introduction to Git functionality in Rstudio
RStudio also has the ability to interact with Git and GitHub, similar to
GitHub Desktop. I will briefly show how to initiate this by creating an
RStudio project. More comprehensive resources can be found
In RStudio go to
File -> New Project ...
Choose the second option:
Existing Directory and select the folder which
Git tab in located in the top right panel. It is empty
because no changes have been made to the repositor.
We don't want to version control the files associated with the RStudio project.
Add the names of these files in the
.gitignore text file as shown in the
screenshot below and save the file.
Git tab you will now notice the
.gitignore file has appeared because
you have made changes to it.
You will also notice these changes in GitHub Desktop.
Describe the commit and click on .
Sync the local repository with the remote by clicking on the button.
RStudio can also handle branches. To see this, click on the branch symbol
, and create
a branch called
gh-pages. To do this, enter
gh-pages in the Name field and click on
In RStudio you should see a dropdown list of branches in the top right hand
corner of the
Git panel. You should now be in the
gh-pages branch for Chapter 7.
Note: this branch must be called
gh-pages; you will find out why in the next chapter
Chapter 7: Create and publish an R Markdown document
In this chapter you will learn how to create an HTML report (of the PCA you did in
earlier chapters) using
R Markdown. You will
then learn how to publish this report online. The following steps must be completed on the
In RStudio, click on the dropdown
list and select
If you don't have the required packages, RStudio will automatically install them.
This screen appears to indicate the installation of required packages to use
Enter a title and author. Ensure that the
Default Output Format is HTML.
To ensure everything is working correctly compile the document by clicking on
This will convert the
R Markdown document to HTML.
You will be prompted to save the file. It must be saved as
If everything is working properly, an HTML document named
index.html will appear.
This is the HTML report, also called a dynamic document that contains both
R code and text.
I have created a sample report which you can see here.
Copy the contents of that report and paste it into the
index.Rmd file, replacing its entire contents.
Click on the button.
The HTML document will automatically load after the document has finished compiling. You can view
this document in your web browser by clicking the
Open in Browser button.
Note the location and filename of the document. It is currently only on your computer, and has not been published online.
Both RStudio and GitHub Desktop have noticed the changes you made to the
In GitHub Desktop, select all the files that have been changed or added, describe the changes and click on
Publish the local changes to your online GitHub repository by clicking the
button in GitHub Desktop.
Head over to the
pcaCars repository in your online GitHub account. Click on the
Branch dropdown list and select the
Notice that the
R Markdown, HTML and related files only appear in the
branch because that where you committed them.
Click on the
Settings tab. You will see a box called
GitHub Pages which says
that your site has been published at
http://username.github.io/pcaCars. Click on the
site to verify that the report has indeed been published online.
Well done. The report has been published online. This makes it extremely easy to send reports to your supervisor or collaborators, without having to send large email attachments with long names indicating the version. Simply commit new changes to the repository, and the report will automatically get updated online.
The website link never changes, and you can simply send an email to your supervisor or collaborators indicating that changes have been made to the document.
There are four important things to note:
- The html document that you want to publish must be on the
gh-pagesbranch. See https://pages.github.com/ for more details.
- The html document must be named
- The name of the website will always have this format: http://username.github.io/nameofrepository
- Every repository you create can have its own website. Let's test this in Chapter 8.
Chapter 8: Create an online CV
In this chapter you will learn how to create an online CV. The template I have shown is for illustration purposes. The main objective here is for you to have a website that has your CV. I highly recommend the advice given by Sherri Rose on Academic CVs for Statistical Science Faculty Positions.
In GitHub Desktop, create a new repository called
cv. Click on
gh-pages branch and click on
Commit the changes in GitHub Desktop. Describe the changes you made and click on .
Click on to push your changes to your online GitHub account.
After entering a description of the repository click on .
Your GitHub Desktop should now be clean.
Go to your online GitHub account and navigate to the
In setting you should see that your site has been published.
Well done. You now have an online CV.
This concludes the tutorial. Well done.
GitHub has evolved into a necessary tool for anyone doing data analysis. It is not uncommon now for employers to prioritize your GitHub portfolio over your CV. This tutorial demonstrates how simple it is to get up and running with GitHub. In addition to having an easy-to-use interface, it allows you to easily create websites and host dynamic documents. I encourage you to adopt this workflow, whether you work in industry or academia, to showcase your work, increase efficiency and ensure reproducibility.