Compose Multiple Transforms into a Chain

Creates a single transform function that applies multiple transformations in sequence. The first function is applied first and the last function is applied last. The result is itself a function that can be passed as the transform argument to il_compare() or il_block_on().

Usage

il_transform(...)

Arguments

...

Two or more functions to compose, in application order. Each must be a recognized transform (e.g. tolower, toupper, trimws, il_soundex, il_metaphone, il_dmetaphone).

Value

A function of class il_transform_chain that applies all transforms in order. The individual steps are stored in the "transforms" attribute.

Details

On the SQL side, the transforms are nested inside-out: il_transform(tolower, trimws) becomes TRIM(LOWER(col)).

Examples

# Lower-case then trim whitespace
tf <- il_transform(tolower, trimws)
tf('  Hello  ')
#> [1] "hello"

# Use in a specification
spec <- il_spec() |>
  il_compare(name, cl_exact(), transform = il_transform(tolower, trimws))