polmineR (version 0.8.9)

context-class: Context class.

Description

Class to organize information of context analysis.

Usage

# S4 method for context
length(x)
# S4 method for context
p_attributes(.Object)
# S4 method for context
count(.Object)
# S4 method for context
sample(x, size)
# S4 method for context
enrich(
  .Object,
  s_attribute = NULL,
  p_attribute = NULL,
  decode = FALSE,
  stat = FALSE,
  verbose = TRUE,
  ...
)
# S4 method for context
as.regions(x, node = TRUE)
# S4 method for 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

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.

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.

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)