tidytext: unnest_tokens – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

unnest_tokens

Split a column into tokens

Description

Split a column into tokens, flattening the table into one-token-per-row. This function supports non-standard evaluation through the tidyeval framework.

Usage

unnest_tokens(
  tbl,
  output,
  input,
  token = "words",
  format = c("text", "man", "latex", "html", "xml"),
  to_lower = TRUE,
  drop = TRUE,
  collapse = NULL,
  ...
)

Arguments

`tbl`	A data frame
`output`	Output column to be created as string or symbol.
`input`	Input column that gets split as string or symbol. The output/input arguments are passed by expression and support quasiquotation; you can unquote strings and symbols.
`token`	Unit for tokenizing, or a custom tokenizing function. Built-in options are "words" (default), "characters", "character_shingles", "ngrams", "skip_ngrams", "sentences", "lines", "paragraphs", "regex", "tweets" (tokenization by word that preserves usernames, hashtags, and URLS ), and "ptb" (Penn Treebank). If a function, should take a character vector and return a list of character vectors of the same length.
`format`	Either "text", "man", "latex", "html", or "xml". When the format is "text", this function uses the tokenizers package. If not "text", this uses the hunspell tokenizer, and can tokenize only by "word"
`to_lower`	Whether to convert tokens to lowercase. If tokens include URLS (such as with `token = "tweets"`), such converted URLs may no longer be correct.
`drop`	Whether original input column should get dropped. Ignored if the original input and new output column have the same name.
`collapse`	A character vector of variables to collapse text across, or `NULL`. For tokens like n-grams or sentences, text can be collapsed across rows within variables specified by `collapse` before tokenization. At tidytext 0.2.7, the default behavior for `collapse = NULL` changed to be more consistent. The new behavior is that text is not collapsed for `NULL`. Grouping data specifies variables to collapse across in the same way as `collapse` but you cannot use both the `collapse` argument and grouped data. Collapsing applies mostly to `token` options of "ngrams", "skip_ngrams", "sentences", "lines", "paragraphs", or "regex".
`...`	Extra arguments passed on to tokenizers, such as `strip_punct` for "words" and "tweets", `n` and `k` for "ngrams" and "skip_ngrams", `strip_url` for "tweets", and `pattern` for "regex".

Details

If format is anything other than "text", this uses the hunspell_parse tokenizer instead of the tokenizers package. This does not yet have support for tokenizing by any unit other than words.

Examples

library(dplyr)
library(janeaustenr)

d <- tibble(txt = prideprejudice)
d

d %>%
  unnest_tokens(word, txt)

d %>%
  unnest_tokens(sentence, txt, token = "sentences")

d %>%
  unnest_tokens(ngram, txt, token = "ngrams", n = 2)

d %>%
  unnest_tokens(chapter, txt, token = "regex", pattern = "Chapter [\\\\d]")

d %>%
  unnest_tokens(shingle, txt, token = "character_shingles", n = 4)

# custom function
d %>%
  unnest_tokens(word, txt, token = stringr::str_split, pattern = " ")

# tokenize HTML
h <- tibble(row = 1:2,
                text = c("<h1>Text <b>is</b>", "<a href='example.com'>here</a>"))

h %>%
  unnest_tokens(word, text, format = "html")

tidytext

Text Mining using 'dplyr', 'ggplot2', and Other Tidy Tools

v0.3.1

MIT + file LICENSE

Authors

Gabriela De Queiroz [ctb], Colin Fay [ctb] (<https://orcid.org/0000-0001-7343-1846>), Emil Hvitfeldt [ctb], Os Keyes [ctb] (<https://orcid.org/0000-0001-5196-609X>), Kanishka Misra [ctb], Tim Mastny [ctb], Jeff Erickson [ctb], David Robinson [aut], Julia Silge [aut, cre] (<https://orcid.org/0000-0002-3671-836X>)

Initial release