compare_corpus: Compare tCorpus vocabulary to that of another (reference)...

In corpustools: Managing, Querying and Analyzing Tokenized Text

Compare tCorpus vocabulary to that of another (reference) tCorpus

Description

Compare tCorpus vocabulary to that of another (reference) tCorpus

Usage

compare_corpus(
  tc,
  tc_y,
  feature,
  smooth = 0.1,
  min_ratio = NULL,
  min_chi2 = NULL,
  is_subset = F,
  yates_cor = c("auto", "yes", "no"),
  what = c("freq", "docfreq", "cooccurrence")
)

Arguments

tc	a tCorpus
tc_y	the reference tCorpus
feature	the column name of the feature that is to be compared
smooth	Laplace smoothing is used for the calculation of the probabilities. Here you can set the added (pseuocount) value.
min_ratio	threshold for the ratio value, which is the ratio of the relative frequency of a term in dtm.x and dtm.y
min_chi2	threshold for the chi^2 value
is_subset	Specify whether tc is a subset of tc_y. In this case, the term frequencies of tc will be subtracted from the term frequencies in tc_y
yates_cor	mode for using yates correctsion in the chi^2 calculation. Can be turned on ("yes") or off ("no"), or set to "auto", in which case cochrans rule is used to determine whether yates' correction is used.
what	choose whether to compare the frequency ("freq") of terms, or the document frequency ("docfreq"). This also affects how chi^2 is calculated, comparing either freq relative to vocabulary size or docfreq relative to corpus size (N)

Value

A vocabularyComparison object

Examples

tc = create_tcorpus(sotu_texts, doc_column = 'id')

tc$preprocess('token', 'feature', remove_stopwords = TRUE, use_stemming = TRUE)

obama = tc$subset_meta(president == 'Barack Obama', copy=TRUE)
bush = tc$subset_meta(president == 'George W. Bush', copy=TRUE)

comp = compare_corpus(tc, bush, 'feature')
comp = comp[order(-comp$chi),]
head(comp)
plot(comp)

corpustools documentation built on May 31, 2023, 8:45 p.m.