gofastr (version 0.3.0)

as_dtm: Coerce Various Object Into a DocumentTermMatrix/TermDocumentMatrix

Description

Convenience functions to convert a objects from different packages into either a tm::DocumentTermMatrix or tm::TermDocumentMatrix object. Grouping variables are used as the row/column names for the DocumentTermMatrix/TermDocumentMatrix.

Usage

as_dtm(x, weighting = tm::weightTf, docs = NULL, pos = TRUE, ...)
as_tdm(x, weighting = tm::weightTf, docs = NULL, pos = TRUE, ...)

Arguments

x

A data object.

weighting

A weighting function capable of handling a tm::DocumentTermMatrix. It defaults to weightTf for term frequency weighting. Available weighting functions shipped with the tm package are weightTf, weightTfIdf, weightBin, and weightSMART.

docs

The vector of integers or character strings denoting document columns.

pos

logical. If TRUE parts of speech will be used. If FALSE the corresponding tokens will be used.

…

ignored.

Value

Returns a tm::DocumentTermMatrix or tm::TermDocumentMatrix object.

Examples

# NOT RUN {
with(partial_republican_debates_2015,
    as_dtm(dialogue, paste(location, element_id, sentence_id, sep = "_"))
)

as_dtm(mtcars)
as_dtm(CO2, docs = c('Plant', 'Type', 'Treatment'))
# }
# NOT RUN {
## termco object to DTM/TDM
library(termco)
as_dtm(markers)
as_dtm(markers,weighting = tm::weightTfIdf)
as_tdm(markers)

cosine_distance <- function (x, ...) {
    x <- t(slam::as.simple_triplet_matrix(x))
    stats::as.dist(1 - slam::crossprod_simple_triplet_matrix(x)/(sqrt(slam::col_sums(x^2) %*%
        t(slam::col_sums(x^2)))))
}


mod <- hclust(cosine_distance(as_dtm(markers)))
plot(mod)
rect.hclust(mod, k = 5, border = "red")

(clusters <- cutree(mod, 5))

## Parts of speech to DTM/TDM
library(tagger)
library(dplyr)
data(presidential_debates_2012_pos)

pos <- presidential_debates_2012_pos %>%
    select_tags(c("NN", "NNP", "NNPS", "NNS"))

as_dtm(pos_text)
as_dtm(pos_text, pos=FALSE)

as_tdm(pos_text)
as_tdm(pos_text, pos=FALSE)

presidential_debates_2012_pos %>%
    as_basic() %>%
    as_dtm()
# }