Version Control with Git

Version control is the lab notebook of the digital world: it’s what professionals use to keep track of what they’ve done and to collaborate with other people. Every large software development project relies on it, and most programmers use it for their small jobs as well. And it isn’t just for software: books, papers, small data sets, and anything that changes over time or needs to be shared can and should be stored in a version control system.

The advantages of version control over, say, emailing files back and forth, are:

• Nothing that is committed to version control is ever lost, unless you work really, really hard at it. Since all old versions of files are saved, it’s always possible to go back in time to see exactly who wrote what on a particular day, or what version of a program was used to generate a particular set of results.

• As we have this record of who made what changes when, we know who to ask if we have questions later on, and, if needed, revert to a previous version, much like the “undo” feature in an editor.

• When several people collaborate in the same project, it’s possible to accidentally overlook or overwrite someone’s changes. The version control system automatically notifies users whenever there’s a conflict between one person’s work and another’s.

Teams are not the only ones to benefit from version control: lone researchers can benefit immensely. Keeping a record of what was changed, when, and why is extremely useful for all researchers if they ever need to come back to the project later on (e.g., a year later, when memory has faded).

Prerequisites

In this lesson we use Git from the Unix Shell. Some previous experience with the shell is expected, but isn’t mandatory.

Git is not Github

It’s important to note that git and github are not the same thing. Git is the version control system, that stores history is a repository. Github is a website that hosts git repositories.

In this workshop we will use git on your local machine first to create a toy experiment, where Alice and Bob will collaborate on creating a Support Vector Machine to classify digits (like MNIST). We’ll then learn how we can store this repo on github.