Regex Extraction Column Transform

Returns a transform that extracts a regex match from a string column. Returns NA when no match is found. The result can be passed as the transform argument to il_compare() or il_block_on(), and composed with other transforms via il_transform(). On DuckDB and PostgreSQL, the computation is pushed into SQL.

Usage

il_regex_extract(pattern, group = 0L)

Arguments

pattern

A regular expression.

group

Integer capture group to extract. Use 0 for the whole match, or a positive integer for a numbered capture group.

Value

An il_column_transform closure.

Examples

# Extract a 5-digit ZIP code from a freeform address string
tf <- il_regex_extract('\\d{5}')
tf(c('Apt 4, 90210', '10001-1234', 'no zip'))
#> [1] "90210" "10001" NA