R: Create a document-feature matrix

dfm {quanteda} | R Documentation

## Create a document-feature matrix

### Description

Construct a sparse document-feature matrix, from a character, corpus, tokens, or even other dfm object.

### Usage

    dfm(
      x,
      tolower = TRUE,
      remove_padding = FALSE,
      verbose = quanteda_options("verbose"),
      ...
    )

### Arguments

`x` | a tokens or dfm object
`tolower` | convert all features to lowercase
`remove_padding` | logical; if `TRUE`, remove the "pads" left as empty tokens after calling `tokens()` or `tokens_remove()` with `padding = TRUE`
`verbose` | display messages if `TRUE`
`...` | not used directly

### Value

a dfm object

### Changes in version 3

In quanteda v3, many convenience functions formerly available in `dfm()` were deprecated. Formerly, `dfm()` could be called directly on a `character` or `corpus` object, but we now steer users to tokenise their inputs first using `tokens()`. Other convenience arguments to `dfm()` were also removed, such as `select`, `dictionary`, `thesaurus`, and `groups`. All of these functions are available elsewhere, e.g. through `dfm_group()`. See `news(Version >= "2.9", package = "quanteda")` for details.

### See Also

`dfm_select()`, dfm

### Examples

    ## for a corpus
    toks <- data_corpus_inaugural %>%
      corpus_subset(Year > 1980) %>%
      tokens()
    dfm(toks)

    # removal options
    toks <- tokens(c("a b c", "A B C D")) %>%
        tokens_remove("b", padding = TRUE)
    toks
    dfm(toks)
    dfm(toks, remove = "") # remove "pads"

    # preserving case
    dfm(toks, tolower = FALSE)

[Package quanteda version 3.0.0 Index]