quanteda (version 0.9.9-3)

textstat_dist: Distance matrix between documents and/or features

Description

These functions compute distance matrix between documents and/or features from a dfm and return a standard dist object.

Usage

textstat_dist(x, selection = character(0), n = NULL, margin = c("documents", "features"), method = "euclidean", upper = TRUE, diag = FALSE, p = 2)
textstat_simil(x, selection = character(0), n = NULL, margin = c("documents", "features"), method = "correlation", upper = FALSE, diag = FALSE)

Arguments

x

a dfm object

selection

character or character vector of document names or feature labels from the dfm

n

the top n highest-ranking items will be returned. If n is NULL, return all items.

margin

identifies the margin of the dfm on which similarity or difference will be computed: documents for documents or features for word/term features.

method

method the distance measure to be used; see Details

upper

whether the upper triangle of the symmetric $V \times V$ matrix is recorded

diag

whether the diagonal of the distance matrix should be recorded

p

The power of the Minkowski distance.

Details

textstat_dist options are: "euclidean" (default), "canberra", "Chisquared", "Chisquared2", "hamming", "kullback". "manhattan", "maximum", "canberra", and "minkowski".

textstat_simil options are: "correlation" (default), "cosine", "jaccard", "eJaccard", "dice", "eDice", "simple matching", "hamann", and "faith".

See Also

dfm

textstat_dist, as.list.dist

Examples

# create a dfm from inaugural addresses from Reagan onwards
presDfm <- dfm(corpus_subset(inaugCorpus, Year > 1980), 
               remove = stopwords("english"), stem = TRUE)
               
## distance

# compute some document distances
(tmp <- textstat_dist(presDfm, margin = "documents"))

# for specific comparisons
textstat_dist(presDfm, "1985-Reagan", n = 5, margin = "documents")
textstat_dist(presDfm, c("2009-Obama" , "2013-Obama"), n = 5, margin = "documents")
textstat_dist(presDfm, c("2009-Obama" , "2013-Obama"), margin = "documents")
textstat_dist(presDfm, "2005-Bush", margin = "documents", method = "eJaccard")

## similarities

# compute some document similarities
(tmp <- textstat_simil(presDfm, margin = "documents"))

# output as a list
as.list(tmp)[1:2]

# for specific comparisons
textstat_simil(presDfm, "1985-Reagan", n = 5, margin = "documents")
textstat_simil(presDfm, c("2009-Obama" , "2013-Obama"), n = 5, margin = "documents")
textstat_simil(presDfm, c("2009-Obama" , "2013-Obama"), margin = "documents")
textstat_simil(presDfm, c("2009-Obama" , "2013-Obama"), margin = "documents", method = "cosine")

# compute some term similarities
textstat_simil(presDfm, c("fair", "health", "terror"), method = "cosine", 
               margin = "features", 20)