Finding Consensus in Two Out of Three Columns and Summarizing Them with R Code

Reshaping Long-Form Data with Pandas: A Comparison of Two Methods

Here's the complete code with all methods:

Melting a Pandas DataFrame from Wide to Long Format Twice on the Same Column

Reshaping DataFrames from Wide to Long Format in R: A Comparison of Two Approaches Using data.table and tidyr

Merging Rows by Subject Number: A Guide to Longing Data in R