Extract pattern matches from documents

ac_extract() returns one list element per document. Each element contains the matched text and the corresponding pattern values.

Usage

ac_extract(ac, doc, ..., overlapping = FALSE, na = c("keep", "empty", "error"))

Arguments

ac

An <ac_automaton> object created by ac_build().

doc

A character vector of documents to search.

...

Must be empty. This is used to require optional arguments to be supplied by name.

overlapping

Default is FALSE. If TRUE, extract overlapping matches. This is only supported when ac was built with match_kind = "standard".

na

How to handle NA documents. "keep" returns one row with missing matches and patterns values (default); "empty" treats missing documents as no matches; "error" fails.

Value

A list with the same length as doc. Each element is a data frame with one row per match and two columns:

• matches: Text matched in the document.

• patterns: Pattern values corresponding to each match.

See also

ac_extract_df(), ac_locate(), ac_detect(), ac_count().

Examples

if (
  requireNamespace("dplyr", quietly = TRUE) &&
    requireNamespace("tibble", quietly = TRUE) &&
    requireNamespace("tidyr", quietly = TRUE)
) {
  ac <- ac_build(c("hello", "world"))
  tibble::tibble(doc = c("hello world", "nothing", "world")) |>
    dplyr::mutate(extracted = ac_extract(ac, doc)) |>
    tidyr::unnest(extracted)
}
#> # A tibble: 3 × 3
#>   doc         matches patterns
#>   <chr>       <chr>   <chr>   
#> 1 hello world hello   hello   
#> 2 hello world world   world   
#> 3 world       world   world