kwic {quanteda}

Locate keywords-in-context

Description

For a text or a collection of texts (in a quanteda corpus object), return a list of a keyword supplied by the user in its immediate context, identifying the source text and the word index number within the source text. (Not the line number, since the text may or may not be segmented using end-of-line delimiters.)

Usage

kwic(
  x,
  pattern,
  window = 5,
  valuetype = c("glob", "regex", "fixed"),
  separator = " ",
  case_insensitive = TRUE,
  index = NULL,
  ...
)

is.kwic(x)

## S3 method for class 'kwic'
as.data.frame(x, ...)

Arguments

x

a character, corpus, or tokens object

pattern

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

window

the number of context words to be displayed around the keyword

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.

separator

a character to separate words in the output

case_insensitive

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

index

an index object to specify keywords

...

unused

Value

A kwic classed data.frame, with the document name (docname) and the token index positions (from and to, which will be the same for single-word patterns, or a sequence equal in length to the number of elements for multi-word phrases).

Note

pattern will be a keyword pattern or phrase, possibly multiple patterns, that may include punctuation. If a pattern contains whitespace, it is best to wrap it in phrase() to make this explicit. However if pattern is a collocations (see quanteda.textstats or dictionary object, then the collocations or multi-word dictionary keys will automatically be considered phrases where each whitespace-separated element matches a token in sequence.

See Also

print-methods

Examples

# single token matching
toks <- tokens(data_corpus_inaugural[1:8])
kwic(toks, pattern = "secure*", valuetype = "glob", window = 3)
kwic(toks, pattern = "secur", valuetype = "regex", window = 3)
kwic(toks, pattern = "security", valuetype = "fixed", window = 3)

# phrase matching
kwic(toks, pattern = phrase("secur* against"), window = 2)
kwic(toks, pattern = phrase("war against"), valuetype = "regex", window = 2)

# use index
idx <- index(toks, phrase("secur* against"))
kwic(toks, index = idx, window = 2)
kw <- kwic(tokens(data_corpus_inaugural[1:20]), "provident*")
is.kwic(kw)
is.kwic("Not a kwic")
is.kwic(kw[, c("pre", "post")])

toks <- tokens(data_corpus_inaugural[1:8])
kw <- kwic(toks, pattern = "secure*", valuetype = "glob", window = 3)
as.data.frame(kw)