Handling Missing Values in DataFrames: A Step-by-Step Guide to Replacing NA with NA Using dplyr Library in R

Using Macros in R DataFrames: An Efficient Way to Represent Specific Values or Expressions

Here is a complete code snippet that combines all the interleaved code you wrote in a nice executable codeblock:

Understanding Vectors in R: A Practical Guide to Storing Multiple Objects

Understanding the Dot Problem in SQLDF and How to Master sqldf's Syntax for Effective Data Manipulation.

Mutating Variables in a data.table by Condition Using Two Variables in Long Format Data

Converting Values Based on Class Variable Using dplyr Package in R

Detecting POSIXct Objects in R: A Flexible Approach to Class Detection

Identifying Alerts in R: A Step-by-Step Guide to Analyzing Stage-Specific Data

Removing Consecutive Duplicates from Strings with R: A Comprehensive Guide