cooccurrentTerms {RcmdrPlugin.temis}

Show terms co-occurrences

Description

Show terms that are the most associated with one or several reference terms.

Usage

cooccurrentTerms(term, dtm, variable = NULL, p = 0.1, n.max = 25,
                 sparsity = 0.95, min.occ = 2)

Arguments

dtm

A document-term matrix.

term

A character vector of length 1 corresponding to the name of a column of dtm.

variable

An optional vector of the same length as the number of rows in dtm, giving the levels by which results should be reported.

p

the maximum probability up to which terms should be reported.

n.max

the maximum number of terms to report for each level.

sparsity

Optional sparsity threshold (between 0 and 1) below which terms should be skipped. See removeSparseTerms from tm.

min.occ

the minimum number of occurrences in the whole dtm below which terms should be skipped.

Details

This function allows printing the terms that are most associated with one or several given terms, according to the document-term matrix of the corpus. Co-occurrent terms are those which are specific to documents which contain the given term(s). The output is the same as that returned by the “Terms specific of levels...” dialog (see specificTermsDlg), using a dummy variable indicating whether the term is present or not in each document.

When a variable is selected, the operation is run separately on each sub-matrix constituted by the documents that are members of the variable level. If the term does not appear in a level, NA is returned.

Value

The result is either a matrix (when variable = NULL) or a list of matrices, one for each level of the chosen variable, with seven columns:

“% Term/Cooc.”:

the percent of the term's occurrences in all terms occurrences in documents where the chosen term is also present.

“% Cooc./Term”:

the percent of the term's occurrences that appear in documents where the chosen term is also present (rather than in documents where it does not appear), i.e. the percent of cooccurrences for the term.

“Global %” or “Level %”:

the percent of the term's occurrences in all terms occurrences in the corpus (or in the subset of the corpus corresponding to the variable level).

“Cooc.”:

the number of cooccurrences of the term.

“Global” or “Level”:

the number of occurrences of the term in the corpus (or in the subset of the corpus corresponding to the variable level).

“t value”:

the quantile of a normal distribution corresponding the probability “Prob.”.

“Prob.”:

the probability of observing such an extreme (high or low) number of occurrences of the term in documents where the chosen term is also present, under an hypergeometric distribution.

See Also

termCoocDlg, specificTerms, DocumentTermMatrix, restrictTermsDlg, termsDictionary, freqTermsDlg