context-class {polmineR}

Context class.

Description

Class to organize information of context analysis.

Usage

## S4 method for signature 'context'
length(x)

## S4 method for signature 'context'
p_attributes(.Object)

## S4 method for signature 'context'
count(.Object)

## S4 method for signature 'context'
sample(x, size)

## S4 method for signature 'context'
enrich(
  .Object,
  s_attribute = NULL,
  p_attribute = NULL,
  decode = FALSE,
  stat = FALSE,
  verbose = TRUE,
  ...
)

## S4 method for signature 'context'
as.regions(x, node = TRUE)

## S4 method for signature 'context'
trim(
  .Object,
  s_attribute = NULL,
  positivelist = NULL,
  p_attribute = p_attributes(.Object),
  regex = FALSE,
  stoplist = NULL,
  fn = NULL,
  verbose = TRUE,
  progress = TRUE,
  ...
)

Arguments

x

A context object.

.Object

A context object.

size

An integer indicating sample size.

s_attribute

The s-attribute(s) to add to data.table in slot cpos.

p_attribute

The p-attribute(s) to add to data.table in slot cpos.

decode

A logical value, whether to convert integer ids to expressive strings.

stat

A logical value, whether to generate / update slot stat from the cpos table.

verbose

A logical, whether to be talkative.

...

To maintain backwards compatibility if argument pAttribute is still used.

node

A logical value, whether to include the node (i.e. query matches) in the region matrix generated when creating a partition from a context-object.

positivelist

Tokens that are required to be present to keep a match.

regex

A logical value, whether arguments positivlist / stoplist are interpreted as regular expressions.

stoplist

Tokens that are used to exclude a match.

fn

A function that will be applied on context tables splitted by match_id.

progress

A logical value, whether to show progress bar

Details

Objects of the class context include a data.table in the slot cpos. The data.table will at least include the columns "match_id", "cpos" and "position".

The length-method will return the number of hits that were achieved.

The enrich()-method can be used to add additional information to the data.table in the cpos-slot of a context-object.

Slots

query

The query examined (character).

count

An integer value, the number of hits for the query.

partition

The partition the context object is based on.

size_partition

The size of the partition, a length-one integer vector.

left

A length-one integer value, the number of tokens to the left of the query match.

right

An integer value, the number of tokens to the right of the query match.

size

A length-one integer value, the number of tokens covered by the context-object, i.e. the number of tokens in the right and left context of the node as well as query matches.

size_match

A length-one integer value, the number of tokens matches by the query. Identical with the value in slot count if the query is not a CQP query.

size_coi

A length-one integer value, the number of tokens in the right and left context of the node (excluding query matches).

size_ref

A length-one integer value, the number of tokens in the partition, without tokens matched and the tokens in the left and right context.

boundary

An s-attribute (character).

p_attribute

The p-attribute of the query (character).

corpus

The CWB corpus used (character).

stat

A data.table, the statistics of the analysis.

encoding

Object of class character, encoding of the corpus.

cpos

A data.table, with the columns match_id, cpos, position, word_id.

method

A character-vector, statistical test used.

call

Object of class character, call that generated the object.

Examples

# Keep matches for 'oil' only if first position to the left is 'crude'
.fn <- function(x) if (x[position == -1L][["word"]] == "crude") x else NULL
crude_oil <- context("REUTERS", "oil") %>%
  enrich(p_attribute = "word", decode = TRUE) %>%
  trim(fn = .fn)