Activity 6 - Pivot!

It is assumed that you have read Chapters 9 and 10, and 12 from R4DS and completed the Derive Information with dplyr Primer.

In this activity, you will:

• Locate and read data or other files into R using the here::here function.
• Restructure datasets into longer and wider formats using {tidyr}.
• Separate and unite columns into a tidy format.
• Dress up data tables to help with human readability.

gather and spread vs pivot_longer and pivot_wider

In the Primer, you learned about the tidyr::gather and tidyr::spread functions. These two functions still exist within the tidyverse; however, they have been superseded and will no longer receive new features. You will often see these “lifecycle” badges on {tidyverse} packages and are meant to provide additional information to users.

Hadley’s introduction to the new pivoting functions can be found at the tidyverse blog.

In the tidyr::gather help documentation (i.e., type ?gather in the Console), we can see how to do similar calls using tidyr::pivot_longer.

df %>% gather("key", "value", x, y, z) is equivalent to df %>% pivot_longer(cols = c(x, y, z), names_to = "key", values_to = "value")

Similarly, in the tidyr::spread help documentation, we can see the similarities to tidyr::pivot_longer.

df %>% spread(key, value) is equivalent to df %>% pivot_wider(names_from = key, values_from = value)

An important thing to recognize between the two pivot_ functions is when we use quotation marks "...".

• For pivot_wider, we are specifying columns that already exist to restructure that information across new columns. Therefore, we do not need to use quotation marks.
• For pivot_longer, we are specifying new columns to restructure the information into. Therefore, we need to use quotation marks.

For this Activity (and in STA 418/518) we will use pivot_longer and pivot_wider.

☑️ Task 1: The Workflow

You may need your PAT that you created in Activity 1. If you misplaced this token, you will need to create a new one prior to beginning the steps below. You can do this by going back to your Activity 1 repo and look at Task 4 or go to my repo’s Task 4.

Remember to take these steps slowly, help each other out, and get a hold of your instructor when you have questions or issues.

1. In this GitHub repo, click on the Fork icon near the upper-right-hand corner. You should be taken a copy of this repo that is in your GitHub account - your page title should be username/activity06-pivoting, where username is replaced with your GitHub username.
2. Click on the green Code button.

• Verify that the drop-down identifies that you are using the HTTPS method (this is probably the default view; otherwise, select “HTTPS”).
• Click on the icon to copy the repo HTTPS information.

3. Log in to the RStudio Workbench.

• Verify that you are in an RStudio session (it doesn’t matter if it is a previous Project session or a “vanilla” RStudio session).

4. Create a new Project. You can do this by clicking on the icon or through the menus (File > New Project…).

• In the New Project Wizard pop-up, select Version Control on the Create Project screen, then select Git on the Create Project from Version Control screen.
• On the Clone Git Repository screen, paste the HTTPS information from (2) into the Repository URL dialog box. It should look like: https://github.com/username/activity06-pivoting.git
• The Project directory name dialog box should automatically populate with your repository name, but sometimes Macs have an issue with this (if so, click into this box and press the command key on your keyboard). It should look something like: activity06-pivoting
• In the Create project as subdirectory of dialog box, click on Browse.
• In the Choose Directory pop-up, navigate to your class-level folder (i.e., you were encouraged to create a folder named either STA418 or STA518) You were also encouraged to create anactivities folder within your class-level folder to help organize our materials. Once you have navigated to the folder you wish this repo to be located, click Choose.
• Verify that the Create project as a directory of dialog box contains the folder location that you previously specified, then click on Create Project.
• You may be asked to login with your GitHub credentials on a Clone Repository pop-up window. Provide your GitHub username and PAT (not your GitHub password) if prompted.

6. After a few seconds, your RStudio session will refresh and you should be in your newly created RStudio Project!

Note that beginning in Activity 7, I will be no longer provide these full steps and will instead be saying:

Fork this repo and clone it to a new RStudio Project.

Remember that more detailed directions are provided in this Activity - I will note/link this in activities after this switch.

Planned Pause Point: If you have any questions, contact your instructor or another group.

☑️ Task 2: Complete the RMarkdown File

The activity06-pivoting.Rmd file contains the directions for this activity. For the rest of this class period, you will complete the RMarkdown document with your neighbor(s). Your instructor will be circling and be available to help when needed.

Note that each person is working in their own repo. We are not worrying about collaborating for the time being and instead will be working on being more comfortable with the workflow for working between RStudio and GitHub.

However, do not continue in this README document until you and your neighbor(s) have completed your .Rmd files.

☑️ Task 3: Reflection

Take 5 minutes to draw a concept map that connects what you have learned about pivot_longer and pivot_wider. For example, here is a concept map for dplyr::select:

Next: Activity 7 will focus on combining information from multiple datasets as well and creating maps!