convert-wrappers: Convenience wrappers for dfm convert

In koheiw/quanteda.core: Quantitative Analysis of Textual Data

Description

To make the usage as consistent as possible with other packages, quanteda also provides shortcut wrappers to convert(), designed to be similar in syntax to analogous commands in the packages to whose format they are converting.

Usage

as.wfm(x)

## S3 method for class 'dfm'
as.wfm(x)

as.DocumentTermMatrix(x)

## S3 method for class 'dfm'
as.DocumentTermMatrix(x)

dfm2austin(x)

dfm2tm(x, weighting = tm::weightTf)

dfm2lda(x, omit_empty = TRUE)

dtm2lda(x, omit_empty = TRUE)

dfm2dtm(x, omit_empty = TRUE)

dfm2stm(x, docvars = NULL, omit_empty = TRUE)

Arguments

x	the dfm to be converted
weighting	a tm weight, see tm::weightTf()
omit_empty	logical; if TRUE, omit empty documents and features from the converted dfm. This is required for some formats (such as STM) that do not accept empty documents. Only used when to = "lda" or to = "topicmodels". For to = "stm" format, omit_empty`` is always TRUE'.
docvars	optional data.frame of document variables used as the meta information in conversion to the stm package format. This aids in selecting the document variables only corresponding to the documents with non-zero counts. Only affects the "stm" format.
...	additional arguments used only by as.DocumentTermMatrix

Details

as.wfm converts a quanteda dfm into the wfm format used by the austin package.

as.DocumentTermMatrix will convert a quanteda dfm into the tm package's DocumentTermMatrix format. Note: The tm package version of as.TermDocumentMatrix() allows a weighting argument, which supplies a weighting function for TermDocumentMatrix(). Here the default is for term frequency weighting. If you want a different weighting, apply the weights after converting using one of the tm functions. For other available weighting functions from the tm package, see TermDocumentMatrix.

dfm2lda provides converts a dfm into the list representation of terms in documents used by the lda package (a list with components "documents" and "vocab" as needed by lda::lda.collapsed.gibbs.sampler()).

dfm2ldaformat provides converts a dfm into the list representation of terms in documents used by the lda package (a list with components "documents" and "vocab" as needed by lda::lda.collapsed.gibbs.sampler()).

Value

A converted object determined by the value of to (see above). See conversion target package documentation for more detailed descriptions of the return formats.

Note

Additional coercion methods to base R objects are also available:

[as.data.frame](x)

converts a dfm into a data.frame

[as.matrix](x)

converts a dfm into a matrix

Examples

corp <- corpus_subset(data_corpus_inaugural, Year > 1970)
dfmat <- dfm(corp)

# shortcut conversion to austin package's wfm format
identical(as.wfm(dfmat), convert(dfmat, to = "austin"))

## Not run: 
# shortcut conversion to tm package's DocumentTermMatrix format
identical(as.DocumentTermMatrix(dfmat), convert(dfmat, to = "tm"))

## End(Not run)

## Not run: 
# shortcut conversion to lda package list format
identical(quanteda.core:::dfm2lda(dfmat), convert(dfmat, to = "lda"))

## End(Not run)

## Not run: 
# shortcut conversion to lda package list format
identical(dfm2ldaformat(dfmat), convert(dfmat, to = "lda"))

## End(Not run)

koheiw/quanteda.core documentation built on Sept. 21, 2020, 3:44 p.m.