Tidyverse and Data Visualization

R Programming

Data wrangling

Data visualization

A hands‑on Tidyverse and data‑visualization exercise in which participants practice converting data frames to tibbles, manipulating and reordering data with dplyr and creating scatterplots with ggplot2. Participants practice factoring levels to control plot ordering, how to customize visual elements and how to save results to files.

Authors

Meeta Mistry

Mary Piper

Radhika Khetani

Will Gammerdinger

Published

May 30, 2025

Keywords

R, tidyverse, dplyr, ggplot2

Exercises

Change the animals data frame to a tibble called animals_tb. Save the row names to a column called animal_names before turning it into a tibble.

Use ggplot2 to plot the animal names (x-axis) versus the speed of the animal (y-axis) in animals_tb using a scatterplot. Customize the plot to display as shown below.

We decide that our plot would look better with the animal names ordered from slowest to fastest. Using the animals_tb tibble, reorder the animals on the x-axis to start with the slowest animal on the left-hand side of the plot to the fastest animal on the right-hand side of the plot by completing the following steps:

a. Use the arrange() function to order the rows by speed from slowest to fastest. Then use the pull() function to extract the animal_names column as a vector of character values. Save the new variable as names_ordered_by_speed.

b. Turn the animal_names column of animals_tb into a factor and specify the levels as names_ordered_by_speed from slowest to fastest (output in part a). Note: this step is crucial, because ggplot2 uses factor as plotting order, instead of the order we observe in data frame.

c. Re-plot the scatterplot with the animal names in order from slowest to fastest.

Note

If you are interested in exploring other ways to reorder a variable in ggplot2, refer to this post.

Save the plot as a PDF called animals_by_speed_scatterplot.pdf to the results folder.
Use the functions from the dplyr package to perform the following tasks:

a. Extract the rows of animals_tb tibble with color of gray or tan, order the rows based from slowest to fastest speed, and save to a variable called animals_gray_tan.

b. Save animals_gray_tan as a comma-separated value file called animals_tb_ordered.csv to the results folder.

Reuse

CC-BY-4.0

--- title: "Tidyverse and Data Visualization" description: | A hands‑on Tidyverse and data‑visualization exercise in which participants practice converting data frames to tibbles, manipulating and reordering data with dplyr and creating scatterplots with `ggplot2`. Participants practice factoring levels to control plot ordering, how to customize visual elements and how to save results to files. author: - Meeta Mistry - Mary Piper - Radhika Khetani - Will Gammerdinger date: "2025-05-30" categories: - R Programming - Data wrangling - Data visualization keywords: - R - tidyverse - dplyr - ggplot2 license: "CC-BY-4.0" editor_options: markdown: wrap: 72 --- ## [**Exercises**](19_Tidyverse_and_data_visualization-Answer_key.qmd) 1. Change the `animals` data frame to a tibble called `animals_tb`. Save the row names to a column called `animal_names` before turning it into a tibble. <img src="../img/animals_tb_unordered.png" width="400"/> 2. Use ggplot2 to plot the animal names (x-axis) versus the speed of the animal (y-axis) in `animals_tb` using a scatterplot. Customize the plot to display as shown below. <img src="../img/animals_unordered_ggplot2.png" width="425"/> 3. We decide that our plot would look better with the animal names ordered from slowest to fastest. Using the `animals_tb` tibble, reorder the animals on the x-axis to start with the slowest animal on the left-hand side of the plot to the fastest animal on the right-hand side of the plot by completing the following steps: **a.** Use the `arrange()` function to order the rows by speed from slowest to fastest. Then use the `pull()` function to extract the `animal_names` column as a vector of character values. Save the new variable as `names_ordered_by_speed`. **b.** Turn the `animal_names` column of `animals_tb` into a factor and specify the levels as `names_ordered_by_speed` from slowest to fastest (output in part a). Note: this step is crucial, because ggplot2 uses `factor` as plotting order, instead of the order we observe in data frame. **c.** Re-plot the scatterplot with the animal names in order from slowest to fastest. <img src="../img/animals_ordered_ggplot2.png" width="425"/> ::: {.callout-note} If you are interested in exploring other ways to reorder a variable in ggplot2, refer to this [post](https://www.r-graph-gallery.com/267-reorder-a-variable-in-ggplot2.html). ::: 4. Save the plot as a PDF called `animals_by_speed_scatterplot.pdf ` to the `results` folder. 5. Use the functions from the `dplyr` package to perform the following tasks: **a.** Extract the rows of `animals_tb` tibble with color of gray or tan, order the rows based from slowest to fastest speed, and save to a variable called `animals_gray_tan`. <img src="../img/animals_tb_ordered.png" width="300"/> **b.** Save `animals_gray_tan` as a comma-separated value file called `animals_tb_ordered.csv` to the `results` folder.