But data.table creator Matt Dowle told me that it’s actually quite simple: Just think of it as a symbol representing “each group.” Let’s go through a couple of examples. I have a data set ...

Inequalities are often used in grouped tables. For example, the category \(0 \textless m \leq 4\) means that \(m\) is larger than 0 but less than or equal to 4. If data is organised into groups ...

For example, the category \(0 \textless m ... In grouped tables the exact number of minutes late cannot be found. As the data has been grouped, the exact data values are not known so only an ...