Introduction to Scientific Computing for Genomics

GCB Academy

Nov 4 – 5, 2019

9am – 5pm

Instructors: Dan Leehr (GCB), Hilmar Lapp (GCB)

Helpers: Valerie Gartner (Biology), Zachery Mielko (UPGG)

General Information

Computing has become an integral and indispensable part of genomic biology. This course teaches basic skills in scientific computing, with a focus on applications for genomic science, aimed at making you more productive, your computational work more reliable, and your research easier to reproduce and extend, including by your future self. The course includes introductions to

  1. using Unix shell commands to efficiently find, organize, and stage data for analysis;
  2. basic data types, control flows, functions, and 3rd party packages for the Python programming language commonly encountered in scientific computing;
  3. using version control to manage with confidence the numerous directions research code takes from inception to publication; and
  4. effectively using a high-performance computing cluster to run computational analyses.
The format of the course is inspired by the acclaimed Software Carpentry-style bootcamps. Hence, this is a fully hands-on workshop, and students are expected to bring a laptop. Participants will be encouraged to help one another and to apply what they have learned to their own research problems.

The Carpentries, of which Software Carpentry is a part, develops and teaches workshops aims to help researchers get their work done in less time and with

For more information on what The Carpentries teach and why, please see the paper "Best Practices for Scientific Computing".

Who: The course is aimed at graduate students, postdocs, early career faculty, and other researchers.

Where: Bostock Library, EDGE Workshop Room. Get directions with OpenStreetMap or Google Maps.

When: Nov 4 – 5, 2019. Add to your Google Calendar.

Requirements: Participants must bring a laptop with a Mac, Linux, or Windows operating system (not a tablet, Chromebook, etc.) that they have administrative privileges on. They should have a few specific software packages installed (listed below). Some basic familiarity with Linux (or Unix), such as from an Introduction to Unix and Bash class, is assumed.

Code of Conduct: Everyone who participates in Carpentries activities is required to conform to the Code of Conduct. This document also outlines how to report an incident if needed.

Accessibility:

Contact: Please email gcb-help@duke.edu for more information.


Surveys

Please be sure to complete these surveys before and after the workshop.

Pre-workshop Survey

Post-workshop Survey


Schedule

Day 1

Before Pre-workshop survey
09:00 Automating Tasks with the Unix Shell
10:30 Morning break
10:45 Automating Tasks with the Unix Shell (Continued)
12:30 Lunch break
13:30 Building Programs with Python
15:00 Afternoon break
15:15 Building Programs with Python (Continued)
16:45 Wrap-up
17:00 END

Day 2

09:00 Version Control with Git
10:30 Morning break
10:45 Version Control with Git (Continued)
12:30 Lunch break
13:30 Running programs on an HPC cluster
15:00 Afternoon break
15:15 Running programs on an HPC cluster (Continued)
16:30 Wrap-up
16:45 Post-workshop Survey
16:50 END

We will use this collaborative document for chatting, taking notes, and sharing URLs and bits of code.


Syllabus

The Unix Shell

  • Files and Directories
  • History and Tab Completion
  • Finding Things
  • Pipes and Redirection
  • Looping Over Files
  • Reference...

Programming in Python

  • Data types and variables
  • Loops and conditionals
  • Creating and Using Functions
  • Working with files
  • Libraries and packages
  • Using Python from the Command Line
  • Reference...

Version Control with Git

  • Creating a Repository
  • Recording Changes to Files: add, commit, ...
  • Viewing Changes: status, diff, ...
  • Ignoring Files
  • Working on the Web: clone, pull, push, ...
  • Resolving Conflicts
  • Open Licenses
  • Where to Host Work, and Why
  • Reference...

Running programs on an HPC cluster

  • Why you need a cluster
  • How a cluster works
  • Running a job: srun
  • Running a batch job: sbatch
  • Monitoring your jobs: squeue, sacct, scancel
  • Moving files in/out: scp
  • Finding/getting software
  • Helpful Resources

Materials

Unix shell

  • See "Setup" under the lesson

Version control

Setup

To participate in this workshop, you will need access to the software described below. In addition, you will need an up-to-date web browser.

We maintain a list of common issues that occur during installation as a reference for instructors that may be useful on the Configuration Problems and Solutions wiki page.

The Bash Shell

Bash is a commonly-used shell that gives you the power to do simple tasks more quickly.

Video Tutorial
  1. Download the Git for Windows installer.
  2. Run the installer and follow the steps below:
    1. Click on "Next" four times (two times if you've previously installed Git). You don't need to change anything in the Information, location, components, and start menu screens.
    2. From the dropdown menu select "Use the nano editor by default" and click on "Next".
    3. Ensure that "Git from the command line and also from 3rd-party software" is selected and click on "Next". (If you don't do this Git Bash will not work properly, requiring you to remove the Git Bash installation, re-run the installer and to select the "Git from the command line and also from 3rd-party software" option.)
    4. Ensure that "Use the native Windows Secure Channel library" is selected and click on "Next".
    5. Ensure that "Checkout Windows-style, commit Unix-style line endings" is selected and click on "Next".
    6. Ensure that "Use Windows' default console window" is selected and click on "Next".
    7. Ensure that "Enable file system caching" and "Enable Git Credential Manager" are selected and click on "Next".
    8. Click on "Install".
    9. Click on "Finish".
  3. If your "HOME" environment variable is not set (or you don't know what this is):
    1. Open command prompt (Open Start Menu then type cmd and press [Enter])
    2. Type the following line into the command prompt window exactly as shown:

      setx HOME "%USERPROFILE%"

    3. Press [Enter], you should see SUCCESS: Specified value was saved.
    4. Quit command prompt by typing exit then pressing [Enter]

This will provide you with both Git and Bash in the Git Bash program.

The default shell in all versions of macOS is Bash, so no need to install anything. You access Bash from the Terminal (found in /Applications/Utilities). See the Git installation video tutorial for an example on how to open the Terminal. You may want to keep Terminal in your dock for this workshop.

The default shell is usually Bash, but if your machine is set up differently you can run it by opening a terminal and typing bash. There is no need to install anything.

Git

Git is a version control system that lets you track who made changes to what when and has options for easily updating a shared or public version of your code on github.com. You will need a supported web browser.

You will need an account at github.com for parts of the Git lesson. Basic GitHub accounts are free. We encourage you to create a GitHub account if you don't have one already. Please consider what personal information you'd like to reveal. For example, you may want to review these instructions for keeping your email address private provided at GitHub.

Git should be installed on your computer as part of your Bash install (described above).

Video Tutorial

For OS X 10.9 and higher, install Git for Mac by downloading and running the most recent "mavericks" installer from this list. Because this installer is not signed by the developer, you may have to right click (control click) on the .pkg file, click Open, and click Open on the pop up window. After installing Git, there will not be anything in your /Applications folder, as Git is a command line program. For older versions of OS X (10.5-10.8) use the most recent available installer labelled "snow-leopard" available here.

If Git is not already available on your machine you can try to install it via your distro's package manager. For Debian/Ubuntu run sudo apt-get install git and for Fedora run sudo dnf install git.

Text Editor

When you're writing code, it's nice to have a text editor that is optimized for writing code, with features like automatic color-coding of key words. The default text editor on macOS and Linux is usually set to Vim, which is not famous for being intuitive. If you accidentally find yourself stuck in it, hit the Esc key, followed by :+Q+! (colon, lower-case 'q', exclamation mark), then hitting Return to return to the shell.

nano is a basic editor and the default that instructors use in the workshop. It is installed along with Git.

Others editors that you can use are Notepad++ or Sublime Text. Be aware that you must add its installation directory to your system path. Please ask your instructor to help you do this.

nano is a basic editor and the default that instructors use in the workshop. See the Git installation video tutorial for an example on how to open nano. It should be pre-installed.

Others editors that you can use are BBEdit or Sublime Text.

nano is a basic editor and the default that instructors use in the workshop. It should be pre-installed.

Others editors that you can use are Gedit, Kate or Sublime Text.

Python

Python is a popular language for research computing, and great for general-purpose programming as well. Installing all of its research packages individually can be a bit difficult, so we recommend Anaconda, an all-in-one installer.

Regardless of how you choose to install it, please make sure you install Python version 3.x (e.g., 3.6 is fine).

We will teach Python using the Jupyter notebook, a programming environment that runs in a web browser. For this to work you will need a reasonably up-to-date browser. The current versions of the Chrome, Safari and Firefox browsers are all supported (some older browsers, including Internet Explorer version 9 and below, are not).

  1. Open https://www.anaconda.com/download/#linux with your web browser.
  2. Download the Python 3 installer for Linux.
    (The installation requires using the shell. If you aren't comfortable doing the installation yourself stop here and request help at the workshop.)
  3. Open a terminal window.
  4. Type
    bash Anaconda3-
    and then press Tab. The name of the file you just downloaded should appear. If it does not, navigate to the folder where you downloaded the file, for example with:
    cd Downloads
    Then, try again.
  5. Press Return. You will follow the text-only prompts. To move through the text, press Spacebar. Type yes and press enter to approve the license. Press enter to approve the default location for the files. Type yes and press enter to prepend Anaconda to your PATH (this makes the Anaconda distribution the default Python).
  6. Close the terminal window.