How to Expand a DataFrame Within a Function Using a Date Sequence in R.

Creating Wide-to-Long DataFrames in R Using Vectorized Operations

Mastering ddply: Powerful Data Manipulation in R with `data.table` Package

Understanding the Issue with ifelse in ddply: Summarize Not Working When Doing Max

Reshaping Cast: A Deeper Dive into Compare and Filter

Using the .() Notation to Simplify dlply Syntax with Multiple Grouping Variables in R