Non-Equi Joins in R

David Selby walks us through non-trivial join scenarios in R:

Most joins are equi-joins, matching rows according to two columns having exactly equal values. These are easy to perfom in R using the base merge() function, the various join() functions in dplyr and the X[i] syntax of data.table.

But sometimes we need non-equi joins or θ-joins, where the matching condition is an interval or a set of inequalities. Other situations call for a rolling join, used to link records according to their proximity in a time sequence.

How do you perform non-equi joins and rolling joins in R?

Click through for the answer using dplyr, sqldf, and data.table. H/T R-bloggers