Both R and Python-Pandas are array-oriented platforms that support fast filtering through vectors of record-id's. In Python-Pandas, such vectors are implemented via Pandas's powerful index construct; in R-data.table, they're accessible through the "which" and "row.name" functions. In both instances, joins to record-id vectors generate fast subsetted access.

How is the record-id vector approach helpful? For starters, the analyst can encapsulate common…