R: Convert 'stm' formatted documents to another format

convertCorpus {stm} | R Documentation

## Convert stm formatted documents to another format

### Description

Takes an stm formatted documents and vocab object and returns formats usable in other packages.

### Usage

    convertCorpus(documents, vocab, type = c("slam", "lda", "Matrix"))

### Arguments

`documents` | the documents object in stm format
`vocab` | the vocab object in stm format
`type` | the output type desired. See Details.

### Details

We also recommend the quanteda and tm packages for text preparation etc. The `convertCorpus` function is provided as a helpful utility for moving formats around, but if you intend to do text processing with a variety of output formats, you likely want to start with quanteda or tm.

The various type conversions are described below:

`type = "slam"`

  Converts to the simple triplet matrix representation used by the slam package. This is the format used internally by tm.

`type = "lda"`

  Converts to the format used by the lda package. This is a very minor change as the format in stm is based on lda's data representation. The difference as noted in `stm` involves how the numbers are indexed. Accordingly this type returns a list containing the new documents object and the unchanged vocab object.

`type = "Matrix"`

  Converts to the sparse matrix representation used by Matrix. This is the format used internally by numerous other text analysis packages.

If you want to write out a file containing the sparse matrix representation popularized by David Blei's `C` code `ldac` see the function `writeLdac`.

### See Also

`writeLdac` `readCorpus` `poliblog5k`

### Examples

    #convert the poliblog5k data to slam package format
    poliSlam <- convertCorpus(poliblog5k.docs, poliblog5k.voc, type="slam")
    class(poliSlam)
    poliMatrix <- convertCorpus(poliblog5k.docs, poliblog5k.voc, type="Matrix")
    class(poliMatrix)
    poliLDA <- convertCorpus(poliblog5k.docs, poliblog5k.voc, type="lda")
    str(poliLDA)

[Package stm version 1.3.6 Index]