index {quanteda}

Locate a pattern in a tokens object

Description

Locates a pattern within a tokens object, returning the index positions of the beginning and ending tokens in the pattern.

Usage

index(
  x,
  pattern,
  valuetype = c("glob", "regex", "fixed"),
  case_insensitive = TRUE
)

is.index(x)

Arguments

x

an input tokens object

pattern

a character vector, list of character vectors, dictionary, or collocations object. See pattern for details.

valuetype

the type of pattern matching: "glob" for "glob"-style wildcard expressions; "regex" for regular expressions; or "fixed" for exact matching. See valuetype for details.

case_insensitive

logical; if TRUE, ignore case when matching a pattern or dictionary values

Value

a data.frame consisting of one row per pattern match, with columns for the document name, index positions from and to, and the pattern matched.

is.index returns TRUE if the object was created by index(); FALSE otherwise.

Examples

toks <- tokens(data_corpus_inaugural[1:8])
index(toks, pattern = "secure*")
index(toks, pattern = c("secure*", phrase("united states"))) |> head()