Grammar of data wrangling

Lecture 4

Dr. Elijah Meyer

Duke University
STA 199 - Spring 2023

January 25, 2023

Checklist

– Clone your ae-03 repo (These will be graded starting today)

– Reminder: AEs due Saturday and Monday 11:59

– Be checking Slack!

Announcements

– HW1 is posted + starter repos created (Due Tuesday: Jan-31)

– Lab 1 is due Friday (Due Friday: Jan-27)

– Missing Repos? Post on Slack.

Slack Questions

In #discussions

– How to make plots show up in plotting tab

– How to get old versions of your document back

Slack Questions

Why are my changes not showing up in the Git tab?

– Are you saving?

– Are you in the correct project

Correct Project

Slack Questions

Don’t have permissions to clone / commit?

– Go back and follow Lab-0 instructions.

– See TA office hours. They will be happy to help!

Margins

In addition, the code should not exceed the 80 character limit, so that all the code can be read when you render to PDF. To help with this, you can add a vertical line at 80 characters by clicking “Tools” “Global Options” “Code” “Display”, then set “Margin Column” to 80, and click “Apply”.

Code Chunk Labels

– Informative names can help when navigating code.

– Informative names do not show up in Rendered documents (and that’s okay!)

Warm Up

These data are from the mtcars data set. In R (or on a scratch piece of paper), practice writing out the code that would generate this plot below. Note: There are three values for cyl: 4, 6, 8.

Warm Up

How could we make this better?

Goals

  • Understand why we need to manipulate data

  • Calculate summary measures for data sets

  • Manipulate the format of data

  • Practice with tidyverse functions

Motivation: We live in a world of big data

– Calculating summary statistics becomes much harder when the data are large

– Often times, we want to “zoom in” to analyze what we want

Application exercise

ae-03-s23

  • Go to the course GitHub org and find your ae-03-s23 (repo name will be suffixed with your GitHub name).

  • Clone the repo in your container, open the Quarto document in the repo, and follow along and complete the exercises.

  • Render, commit, and push your edits by the AE deadline – 3 days from today.

  • This is a long ae. Whatever we get through is what will be what’s due. We will finish the ae on Friday.

Recap of AE

  • We can transform data to learn more about what’s going on

  • Data are messy. This are valuable tools to tell the story you want

🔗 sta199-s23-2.github.io