kwic: Locate keywords-in-context

In koheiw/quanteda.core: Quantitative Analysis of Textual Data

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,
  ...
)

is.kwic(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	character to separate words in the output
case_insensitive	logical; if TRUE, ignore case when matching a pattern or dictionary values
...	additional arguments passed to tokens, for applicable object types

Value

A kwic classed data.frame, with the document name (docname), 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), the context before (pre), the keyword in its original format (keyword, preserving case and attached punctuation), and the context after (post). The return object has its own print method, plus some special attributes that are hidden in the print view. If you want to turn this into a simple data.frame, simply wrap the result in data.frame.

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 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.

Examples

head(kwic(data_corpus_inaugural, pattern = "secure*", window = 3, valuetype = "glob"))
head(kwic(data_corpus_inaugural, pattern = "secur", window = 3, valuetype = "regex"))
head(kwic(data_corpus_inaugural, pattern = "security", window = 3, valuetype = "fixed"))

toks <- tokens(data_corpus_inaugural)
kwic(data_corpus_inaugural, pattern = phrase("war against"))
kwic(data_corpus_inaugural, pattern = phrase("war against"), valuetype = "regex")

kw <- kwic(data_corpus_inaugural, "provident*")
is.kwic(kw)
is.kwic("Not a kwic")
is.kwic(kw[, c("pre", "post")])

koheiw/quanteda.core documentation built on Sept. 21, 2020, 3:44 p.m.