chunkexpr: Chunk an expression
In ffbase: Basic Statistical Functions for Package 'ff'

chunkexpr replaces variables in an expression with a indexed version. It main use it to rewrite "normal" R expression into chunked versions that can be evaluated in a chunked-for-loop.

1	chunkexpr(expr, x = all.vars(expr), i = ".i", prefix = "")

`expr`	`expression` vector or language object
`x`	`character` with variables to be chunked
`i`	name of index that will be used in the for loop, typically a `ri` or `hi`.
`prefix`	prefix for variables to be replaced.