Creating a Design Matrix with Levels from Training Set but Not Test Set

Here is the code for the documentation:

Preparing Data for Creating Spaghetti Plots with R and Tidyverse Library

Understanding Issues with the ess-toggle_underscore Feature in Emacs's Essential Mode

Adding Background Shading or Major Tick Marks in R ggplot Line Graph Using geom_tile()

Creating Dummy Variables for a Dataset in R: A Step-by-Step Guide

How to Write Data by Groups While Skipping the Group Column in R Using dplyr and Purrr Libraries

Resolving Errors While Working with NuPoP Package in R: A Step-by-Step Guide

Reading Last Sheets from Excel Files in R: A Step-by-Step Guide

Understanding the Issue with t.test in R: A Guide to Handling Missing Values and Non-Numeric Columns