Package 'textrecipes'

Description

all_tokenized() selects all token variables, all_tokenized_predictors() selects all predictor token variables.

Usage

all_tokenized()

all_tokenized_predictors()

See Also

recipes::has_role()

Description

List of all feature counting functions

Usage

count_functions

Format

Named list of all ferature counting functions

n_words

Number of words.

n_uq_words

Number of unique words.

n_charS

Number of characters. Not counting urls, hashtags, mentions or white spaces.

n_uq_charS

Number of unique characters. Not counting urls, hashtags, mentions or white spaces.

n_digits

Number of digits.

n_hashtags

Number of hashtags, word preceded by a '#'.

n_uq_hashtags

Number of unique hashtags, word preceded by a '#'.

n_mentions

Number of mentions, word preceded by a '@'.

n_uq_mentions

Number of unique mentions, word preceded by a '@'.

n_commas

Number of commas.

n_periods

Number of periods.

n_exclaims

Number of exclamation points.

n_extraspaces

Number of times 2 or more consecutive whitespace characters (spaces, tabs, or newlines) have been used in a row.

n_caps

Number of upper case characters.

n_lowers

Number of lower case characters.

n_urls

Number of urls.

n_uq_urls

Number of unique urls.

n_nonasciis

Number of non ascii characters.

n_puncts

Number of punctuations characters, not including exclamation points, periods and commas.

first_person

Number of "first person" words.

first_personp

Number of "first person plural" words.

second_person

Number of "second person" words.

second_personp

Number of "second person plural" words.

third_person

Number of "third person" words.

to_be

Number of "to be" words.

prepositions

Number of preposition words.

Details

In this function we refer to "first person", "first person plural" and so on. This list describes what words are contained in each group.

first person

I, me, myself, my, mine, this.

first person plural

we, us, our, ours, these.

second person

you, yours, your, yourself.

second person plural

he, she, it, its, his, hers.

third person

they, them, theirs, their, they're, their's, those, that.

to be

am, is, are, was, were, being, been, be, were, be.

prepositions

about, below, excepting, off, toward, above, beneath, on, under, across, from, onto, underneath, after, between, in, out, until, against, beyond, outside, up, along, but, inside, over, upon, among, by, past, around, concerning, regarding, with, at, despite, into, since, within, down, like, through, without, before, during, near, throughout, behind, except, of, to, for.

All of the functions below propagate missing values: if an input element is NA, the corresponding output element is NA as well.

Description

These functions create the engine object passed to step_sentence_embeddings(). An engine describes how character vectors are turned into numeric embeddings. Engines only hold a reference to the model (a function, or later a model name and server settings), never the model itself, so a prepped recipe stays small.

Usage

embedding_custom(fun)

Arguments

Details

embedding_custom() is the escape hatch for any backend that doesn't have a dedicated engine. The function is called with the unique, non-missing strings that haven't been embedded yet in the current R session, and must return a numeric matrix with exactly one row per string.

The function is stored in the recipe. If it captures a live external object, such as a Python model through reticulate, that object will not survive saveRDS(). Have the function load its model lazily, from a path or an identifier, instead of capturing it.

Value

An object of class sentence_embedding_engine.

See Also

step_sentence_embeddings()

Other Embedding Engines: embedding_ollama()

Examples

# A toy embedder that returns the length and number of vowels of each string
toy_embedder <- function(x) {
  cbind(
    nchar = nchar(x),
    vowels = nchar(gsub("[^aeiou]", "", x))
  )
}

embedding_custom(toy_embedder)

Description

embedding_ollama() creates an engine for step_sentence_embeddings() that gets embeddings from a running Ollama server. No Python environment or API key is needed, the engine sends HTTP requests to the server, which is usually running on your own machine.

Usage

embedding_ollama(
  model,
  host = "http://localhost:11434",
  text_prefix = NULL,
  normalize = FALSE,
  batch_size = 64
)

Arguments

Details

Embeddings are requested from the ⁠/api/embed⁠ endpoint. Requests that fail with a transient error (too many requests, or the server being unavailable) are retried a few times. Any other failure stops bake() with an error, so partial results are never returned. Texts longer than the context length of the model are an error rather than being silently truncated.

Before any text is embedded, the engine checks that the server can be reached and that model is available on it, and gives an error that says how to fix it if not. The text is sent to the server at host. For a server you don't control, keep in mind that this is where your data goes.

The engine stores the model name and the server address, not the model. A prepped recipe therefore needs the same model to be available on the server when it is baked, and Ollama model names, such as "all-minilm", can point to different model versions over time. The engine doesn't pin a version.

Requires the httr2 package.

Value

An object of class sentence_embedding_engine.

Setting up Ollama

The engine needs an Ollama server that is running and has the model.

1. Install Ollama from https://ollama.com/download. See the Ollama documentation for your system.

2. Make sure the server is running. The desktop apps start it when you open them. Otherwise run ⁠ollama serve⁠ in a terminal and leave it running.

3. Pull the model once, for example ⁠ollama pull all-minilm⁠. Models are listed at https://ollama.com/library.

You can check which models are on the server with ⁠ollama list⁠.

See Also

step_sentence_embeddings()

Other Embedding Engines: embedding_custom()

Examples

# Needs a running Ollama server with the model pulled:
#   ollama pull all-minilm
library(recipes)

sample_data <- tibble(
  text = c("The cat sat.", "A dog ran.", "Stocks fell sharply today.")
)

rec <- recipe(~text, data = sample_data) |>
  step_sentence_embeddings(
    text,
    engine = embedding_ollama("all-minilm")
  )

rec |>
  prep() |>
  bake(new_data = NULL)

Description

This data set is primarily used for examples.

Usage

emoji_samples

Format

tibble with 1 column

Description

Returns the tokens as a list of character vectors of a recipe. This function can be useful for diagnostics during recipe construction but should not be used in final recipe steps. Note that this function will both prep() and bake() the recipe it is used on.

Usage

show_tokens(rec, var, n = 6L)

Arguments

Value

A list of character vectors

Examples

text_tibble <- tibble(text = c("This is words", "They are nice!"))

recipe(~text, data = text_tibble) |>
  step_tokenize(text) |>
  show_tokens(text, n = 2)

library(modeldata)
data(tate_text)

recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  show_tokens(medium)

Description

step_clean_levels() creates a specification of a recipe step that will clean nominal data (character or factor) so the levels consist only of letters, numbers, and the underscore.

Usage

step_clean_levels(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  clean = NULL,
  skip = FALSE,
  id = rand_id("clean_levels")
)

Arguments

Details

The levels are cleaned with janitor::make_clean_names(), which is the function responsible for the cleaning, and then reset with dplyr::recode_factor(). When data to be processed contains novel levels (i.e., not contained in the training set), they are converted to missing.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, orginal, value, and id:

terms

character, the selectors or variables selected

original

character, the original levels

value

character, the cleaned levels

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_clean_names(), recipes::step_factor2string(), recipes::step_string2factor(), recipes::step_regex(), recipes::step_unknown(), recipes::step_novel(), recipes::step_other()

Other Steps for Text Cleaning: step_clean_names()

Examples

library(recipes)
library(modeldata)
data(Smithsonian)

smith_tr <- Smithsonian[1:15, ]
smith_te <- Smithsonian[16:20, ]

rec <- recipe(~., data = smith_tr)

rec <- rec |>
  step_clean_levels(name)
rec <- prep(rec, training = smith_tr)

cleaned <- bake(rec, smith_tr)

tidy(rec, number = 1)

# novel levels are replaced with missing
bake(rec, smith_te)

Description

step_clean_names() creates a specification of a recipe step that will clean variable names so the names consist only of letters, numbers, and the underscore.

Usage

step_clean_names(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  clean = NULL,
  skip = FALSE,
  id = rand_id("clean_names")
)

Arguments

Details

The variable names are cleaned with janitor::make_clean_names(), which is the function responsible for the cleaning.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, value, and id:

terms

character, the new clean variable names

value

character, the original variable names

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_clean_levels(), recipes::step_factor2string(), recipes::step_string2factor(), recipes::step_regex(), recipes::step_unknown(), recipes::step_novel(), recipes::step_other()

Other Steps for Text Cleaning: step_clean_levels()

Examples

library(recipes)
data(airquality)

air_tr <- tibble(airquality[1:100, ])
air_te <- tibble(airquality[101:153, ])

rec <- recipe(~., data = air_tr)

rec <- rec |>
  step_clean_names(all_predictors())
rec <- prep(rec, training = air_tr)
tidy(rec, number = 1)

bake(rec, air_tr)
bake(rec, air_te)

Description

step_dummy_hash() creates a specification of a recipe step that will convert factors or character columns into a series of binary (or signed binary) indicator columns.

Usage

step_dummy_hash(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  signed = TRUE,
  num_terms = 32L,
  collapse = FALSE,
  prefix = "dummyhash",
  sparse = "auto",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("dummy_hash")
)

Arguments

Details

Feature hashing, or the hashing trick, is a transformation of a text variable into a new set of numerical variables. This is done by applying a hashing function over the values of the factor levels and using the hash values as feature indices. This allows for a low memory representation of the data and can be very helpful when a qualitative predictor has many levels or is expected to have new levels during prediction. This implementation is done using the MurmurHash3 method via text2vec::hash_vectorizer().

The argument num_terms controls the number of indices that the hashing function will map to. This is the tuning parameter for this transformation. Since the hashing function can map two different tokens to the same index, a higher value of num_terms will result in a lower chance of collision.

The new columns will have names that begin with prefix, then the name of the variable, then the index of the hash, all separated by ⁠_⁠. The indices are padded with zeros to the same width. For example, with the default prefix = "dummyhash" and a variable named text, num_terms = 12 gives dummyhash_text_01 to dummyhash_text_12. If collapse = TRUE, the variable name is replaced by the names of all selected variables joined by ⁠_⁠, such as dummyhash_text_g_01 when text and g are selected.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, value, num_terms, collapse, and id:

terms

character, the selectors or variables selected

value

logical, whether a signed hashing was performed

num_terms

integer, number of terms

collapse

logical, were the columns collapsed

id

character, id of this step

Tuning Parameters

This step has 2 tuning parameters:

• signed: Signed Hash Value (type: logical, default: TRUE)

• num_terms: # Hash Features (type: integer, default: 32)

Sparse data

This step produces sparse columns if sparse = "yes" is being set. The default value "auto" won't trigger production of sparse columns if a recipe is recipes::prep()ed, but allows for a workflow to toggle to "yes" or "no" depending on whether the model supports recipes::sparse_data and if the model is expected to run faster with the data.

The mechanism for determining how much sparsity is produced isn't perfect, and there will be times when you want to manually overwrite by setting sparse = "yes" or sparse = "no".

Case weights

The underlying operation does not allow for case weights.

References

Kilian Weinberger; Anirban Dasgupta; John Langford; Alex Smola; Josh Attenberg (2009).

Kuhn and Johnson (2019), Chapter 7, https://bookdown.org/max/FES/encoding-predictors-with-many-categories.html

See Also

recipes::step_dummy()

Other Steps for Numeric Variables From Characters: step_sentence_embeddings(), step_sequence_onehot(), step_textfeature()

Examples

library(recipes)
library(modeldata)
data(grants)

grants_rec <- recipe(~sponsor_code, data = grants_other) |>
  step_dummy_hash(sponsor_code)

grants_obj <- grants_rec |>
  prep()

bake(grants_obj, grants_test)

tidy(grants_rec, number = 1)
tidy(grants_obj, number = 1)

Description

step_lda() creates a specification of a recipe step that will return the lda dimension estimates of a text variable.

Usage

step_lda(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  lda_models = NULL,
  num_topics = 10L,
  prefix = "lda",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("lda")
)

Arguments

Details

The new columns will have names that begin with prefix, then the name of the variable, then the index of the topic, all separated by ⁠_⁠. For example, with the default prefix = "lda" and a variable named text, the columns will be named lda_text_1, lda_text_2, and so on up to num_topics.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, num_topics, and id:

terms

character, the selectors or variables selected

num_topics

integer, number of topics

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

Source

https://arxiv.org/abs/1301.3781

See Also

Other Steps for Numeric Variables From Tokens: step_texthash(), step_tf(), step_tfidf(), step_word_embeddings()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_lda(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL) |>
  slice(1:2)
tidy(tate_rec, number = 2)
tidy(tate_obj, number = 2)

# Changing the number of topics.
recipe(~., data = tate_text) |>
  step_tokenize(medium, artist) |>
  step_lda(medium, artist, num_topics = 20) |>
  prep() |>
  bake(new_data = NULL) |>
  slice(1:2)

# Supplying A pre-trained LDA model trained using text2vec
library(text2vec)
tokens <- word_tokenizer(tolower(tate_text$medium))
it <- itoken(tokens, ids = seq_along(tate_text$medium))
v <- create_vocabulary(it)
dtm <- create_dtm(it, vocab_vectorizer(v))
lda_model <- LDA$new(n_topics = 15)

recipe(~., data = tate_text) |>
  step_tokenize(medium, artist) |>
  step_lda(medium, artist, lda_models = lda_model) |>
  prep() |>
  bake(new_data = NULL) |>
  slice(1:2)

Description

step_lemma() creates a specification of a recipe step that will extract the lemmatization of a token variable.

Usage

step_lemma(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  skip = FALSE,
  id = rand_id("lemma")
)

Arguments

Details

This stem doesn't perform lemmatization by itself, but rather lets you extract the lemma attribute of the token variable. To be able to use step_lemma you need to use a tokenization method that includes lemmatization. Currently using the "spacyr" engine in step_tokenize() provides lemmatization and works well with step_lemma.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms and id:

terms

character, the selectors or variables selected

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Token Modification: step_ngram(), step_pos_filter(), step_stem(), step_stopwords(), step_tokenfilter(), step_tokenmerge()

Examples

## Not run: 
library(recipes)

short_data <- data.frame(text = c(
  "This is a short tale,",
  "With many cats and ladies."
))

rec_spec <- recipe(~text, data = short_data) |>
  step_tokenize(text, engine = "spacyr") |>
  step_lemma(text) |>
  step_tf(text)

rec_prepped <- prep(rec_spec)

bake(rec_prepped, new_data = NULL)

## End(Not run)

Description

step_ngram() creates a specification of a recipe step that will convert a token variable into a token variable of ngrams.

Usage

step_ngram(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  num_tokens = 3L,
  min_num_tokens = 3L,
  delim = "_",
  skip = FALSE,
  id = rand_id("ngram")
)

Arguments

Details

The use of this step will leave the ordering of the tokens meaningless. If min_num_tokens < num_tokens then the tokens will be ordered in increasing fashion with respect to the number of tokens in the n-gram. If min_num_tokens = 1 and num_tokens = 3 then the output will contain all the 1-grams followed by all the 2-grams followed by all the 3-grams.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms and id:

terms

character, the selectors or variables selected

id

character, id of this step

Tuning Parameters

This step has 1 tuning parameters:

• num_tokens: Number of tokens (type: integer, default: 3)

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Token Modification: step_lemma(), step_pos_filter(), step_stem(), step_stopwords(), step_tokenfilter(), step_tokenmerge()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_ngram(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

tidy(tate_rec, number = 2)
tidy(tate_obj, number = 2)

Description

step_pos_filter() creates a specification of a recipe step that will filter a token variable based on part of speech tags.

Usage

step_pos_filter(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  keep_tags = "NOUN",
  remove_tags = NULL,
  skip = FALSE,
  id = rand_id("pos_filter")
)

Arguments

Details

Possible part of speech tags for spacyr engine are: "ADJ", "ADP", "ADV", "AUX", "CONJ", "CCONJ", "DET", "INTJ", "NOUN", "NUM", "PART", "PRON", "PROPN", "PUNCT", "SCONJ", "SYM", "VERB", "X" and "SPACE". For more information look here https://github.com/explosion/spaCy/blob/master/spacy/glossary.py.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms and id:

terms

character, the selectors or variables selected

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Token Modification: step_lemma(), step_ngram(), step_stem(), step_stopwords(), step_tokenfilter(), step_tokenmerge()

Examples

## Not run: 
library(recipes)

short_data <- data.frame(text = c(
  "This is a short tale,",
  "With many cats and ladies."
))

rec_spec <- recipe(~text, data = short_data) |>
  step_tokenize(text, engine = "spacyr") |>
  step_pos_filter(text, keep_tags = "NOUN") |>
  step_tf(text)

rec_prepped <- prep(rec_spec)

bake(rec_prepped, new_data = NULL)

## End(Not run)

Description

step_sentence_embeddings() creates a specification of a recipe step that will convert a character variable into dense embedding dimensions by running each string through an embedding model.

Usage

step_sentence_embeddings(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  engine,
  prefix = "sentembed",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("sentence_embeddings")
)

Arguments

Details

Unlike step_word_embeddings(), which looks up and aggregates the vectors of tokens, this step takes a character (or factor) column directly and returns one dense vector per row, as produced by the embedding model. It doesn't use step_tokenize().

The new columns have names that begin with prefix, then the name of the variable being embedded, then the position of the dimension. For example, using the default prefix and a variable named text, the new columns are sentembed_text_1, sentembed_text_2, etc.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

What is stored in the recipe

Embedding models are large, so the step never stores the model. It stores the engine, which is a reference to the model, together with the number of dimensions seen when the recipe was prepped. This keeps prepped recipes small, but it also means a prepped recipe can only be baked where the engine can run. A recipe that is moved to another machine needs whatever the engine depends on to be available there.

If the engine returns a different number of dimensions when baking than it did when prepping, bake() errors instead of returning columns the downstream model wasn't trained on.

Missing values and caching

Missing values stay missing: a row with NA text gets NA in all of its embedding columns, and is never sent to the engine. Empty strings are sent to the engine as they are.

Embedding is usually the slowest part of a recipe, and bake() embeds new data every time it is called. Within an R session, embeddings are cached per engine and string, so repeated strings, and the training data that is embedded both by prep() and by bake(), are only embedded once. The cache lives outside the recipe and is cleared when the R session ends.

Tidying

When you tidy() this step, a tibble is returned with columns terms, engine, model, dimension, and id:

terms

character, the selectors or variables selected

engine

character, the name of the engine

model

character, the name of the model, NA if the engine doesn't have one

dimension

integer, the number of embedding dimensions, NA until the recipe is prepped

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

embedding_custom() for the available engines, and step_word_embeddings() for embeddings that are aggregated from tokens.

Other Steps for Numeric Variables From Characters: step_dummy_hash(), step_sequence_onehot(), step_textfeature()

Examples

library(recipes)

# A toy embedder, replace it with a call to a real embedding model
toy_embedder <- function(x) {
  cbind(
    nchar = nchar(x),
    vowels = nchar(gsub("[^aeiou]", "", x))
  )
}

sample_data <- tibble(
  text = c("The cat.", "The cat ran.", "A longer sentence here."),
  text_label = c("short", "short", "long")
)

rec <- recipe(text_label ~ ., data = sample_data) |>
  step_sentence_embeddings(text, engine = embedding_custom(toy_embedder))

obj <- rec |>
  prep()

bake(obj, new_data = NULL)

tidy(rec, number = 1)
tidy(obj, number = 1)

Description

step_sequence_onehot() creates a specification of a recipe step that will take a string and do one hot encoding for each character by position.

Usage

step_sequence_onehot(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  sequence_length = 100,
  padding = "pre",
  truncating = "pre",
  vocabulary = NULL,
  prefix = "seq1hot",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("sequence_onehot")
)

Arguments

Details

The string will be capped by the sequence_length argument, strings shorter then sequence_length will be padded with empty characters. The encoding will assign an integer to each character in the vocabulary, and will encode accordingly. Characters not in the vocabulary will be encoded as 0.

The new columns will have names that begin with prefix, then the name of the variable, then the position in the sequence, all separated by ⁠_⁠. For example, with the default prefix = "seq1hot", a variable named text, and sequence_length = 3, the columns will be named seq1hot_text_1, seq1hot_text_2, and seq1hot_text_3.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, vocabulary, token, and id:

terms

character, the selectors or variables selected

vocabulary

integer, index

token

character, text corresponding to the index

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

Source

https://papers.nips.cc/paper/5782-character-level-convolutional-networks-for-text-classification.pdf

See Also

Other Steps for Numeric Variables From Characters: step_dummy_hash(), step_sentence_embeddings(), step_textfeature()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~medium, data = tate_text) |>
  step_tokenize(medium) |>
  step_tokenfilter(medium) |>
  step_sequence_onehot(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL)

tidy(tate_rec, number = 3)
tidy(tate_obj, number = 3)

Description

step_stem() creates a specification of a recipe step that will convert a token variable to have its stemmed version.

Usage

step_stem(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  options = list(),
  custom_stemmer = NULL,
  skip = FALSE,
  id = rand_id("stem")
)

Arguments

Details

Words tend to have different forms depending on context, such as organize, organizes, and organizing. In many situations it is beneficial to have these words condensed into one to allow for a smaller pool of words. Stemming is the act of chopping off the end of words using a set of heuristics.

Note that the stemming will only be done at the end of the word and will therefore not work reliably on ngrams or sentences.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, is_custom_stemmer, and id:

terms

character, the selectors or variables selected

is_custom_stemmer

logical, indicate if custom stemmer was used

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Token Modification: step_lemma(), step_ngram(), step_pos_filter(), step_stopwords(), step_tokenfilter(), step_tokenmerge()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_stem(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

tidy(tate_rec, number = 2)
tidy(tate_obj, number = 2)

# Using custom stemmer. Here a custom stemmer that removes the last letter
# if it is a "s".
remove_s <- function(x) gsub("s$", "", x)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_stem(medium, custom_stemmer = remove_s)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

Description

step_stopwords() creates a specification of a recipe step that will filter a token variable for stop words.

Usage

step_stopwords(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  language = "en",
  keep = FALSE,
  stopword_source = "snowball",
  custom_stopword_source = NULL,
  skip = FALSE,
  id = rand_id("stopwords")
)

Arguments

Details

Stop words are words which sometimes are removed before natural language processing tasks. While stop words usually refers to the most common words in the language there is no universal stop word list.

The argument custom_stopword_source allows you to pass a character vector to filter against. With the keep argument one can specify words to keep instead of removing thus allowing you to select words with a combination of these two arguments.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, value, keep, and id:

terms

character, the selectors or variables selected

value

character, name of stop word list

keep

logical, whether stop words are removed or kept

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Token Modification: step_lemma(), step_ngram(), step_pos_filter(), step_stem(), step_tokenfilter(), step_tokenmerge()

Examples

library(recipes)
library(modeldata)
data(tate_text)
tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_stopwords(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

tidy(tate_rec, number = 2)
tidy(tate_obj, number = 2)

# With a custom stop words list

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_stopwords(medium, custom_stopword_source = c("twice", "upon"))
tate_obj <- tate_rec |>
  prep(traimomg = tate_text)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

Description

step_text_normalization() creates a specification of a recipe step that will perform Unicode Normalization on character variables.

Usage

step_text_normalization(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  normalization_form = "nfc",
  skip = FALSE,
  id = rand_id("text_normalization")
)

Arguments

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, normalization_form, and id:

terms

character, the selectors or variables selected

normalization_form

character, type of normalization

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_texthash() for feature hashing.

Examples

library(recipes)

sample_data <- tibble(text = c("sch\U00f6n", "scho\U0308n"))

rec <- recipe(~., data = sample_data) |>
  step_text_normalization(text)

prepped <- rec |>
  prep()

bake(prepped, new_data = NULL, text) |>
  slice(1:2)

bake(prepped, new_data = NULL) |>
  slice(2) |>
  pull(text)

tidy(rec, number = 1)
tidy(prepped, number = 1)

Description

step_textfeature() creates a specification of a recipe step that will extract a number of numeric features of a text column.

Usage

step_textfeature(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  extract_functions = count_functions,
  prefix = "textfeature",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("textfeature")
)

Arguments

Details

This step will take a character column and returns a number of numeric columns equal to the number of functions in the list passed to the extract_functions argument.

All the functions passed to extract_functions must take a character vector as input and return a numeric vector of the same length, otherwise an error will be thrown.

The new columns will have names that begin with prefix, then the name of the variable, then the name of the function in extract_functions, all separated by ⁠_⁠. For example, with the default prefix = "textfeature", a variable named text, and the default count_functions, the columns will include textfeature_text_n_words and textfeature_text_n_uq_words.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, functions, and id:

terms

character, the selectors or variables selected

functions

character, name of feature functions

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

Other Steps for Numeric Variables From Characters: step_dummy_hash(), step_sentence_embeddings(), step_sequence_onehot()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_textfeature(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  pull(textfeature_medium_n_words)

tidy(tate_rec, number = 1)
tidy(tate_obj, number = 1)

# Using custom extraction functions
nchar_round_10 <- function(x) round(nchar(x) / 10) * 10

recipe(~., data = tate_text) |>
  step_textfeature(medium,
    extract_functions = list(nchar10 = nchar_round_10)
  ) |>
  prep() |>
  bake(new_data = NULL)

Description

step_texthash() creates a specification of a recipe step that will convert a token variable into multiple numeric variables using the hashing trick.

Usage

step_texthash(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  signed = TRUE,
  num_terms = 1024L,
  prefix = "texthash",
  sparse = "auto",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("texthash")
)

Arguments

Details

Feature hashing, or the hashing trick, is a transformation of a text variable into a new set of numerical variables. This is done by applying a hashing function over the tokens and using the hash values as feature indices. This allows for a low memory representation of the text. This implementation is done using the MurmurHash3 method via text2vec::hash_vectorizer().

The argument num_terms controls the number of indices that the hashing function will map to. This is the tuning parameter for this transformation. Since the hashing function can map two different tokens to the same index, will a higher value of num_terms result in a lower chance of collision.

The new columns will have names that begin with prefix, then the name of the variable, then the index of the hash, all separated by ⁠_⁠. The indices are padded with zeros to the same width. For example, with the default prefix = "texthash" and a variable named text, num_terms = 12 gives texthash_text_01 to texthash_text_12, and num_terms = 101 gives texthash_text_001 to texthash_text_101.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, value and id:

terms

character, the selectors or variables selected

value

logical, is it signed?

length

integer, number of terms

id

character, id of this step

Tuning Parameters

This step has 2 tuning parameters:

• signed: Signed Hash Value (type: logical, default: TRUE)

• num_terms: # Hash Features (type: integer, default: 1024)

Sparse data

This step produces sparse columns if sparse = "yes" is being set. The default value "auto" won't trigger production of sparse columns if a recipe is recipes::prep()ed, but allows for a workflow to toggle to "yes" or "no" depending on whether the model supports recipes::sparse_data and if the model is expected to run faster with the data.

The mechanism for determining how much sparsity is produced isn't perfect, and there will be times when you want to manually overwrite by setting sparse = "yes" or sparse = "no".

Case weights

The underlying operation does not allow for case weights.

References

Kilian Weinberger; Anirban Dasgupta; John Langford; Alex Smola; Josh Attenberg (2009).

See Also

step_tokenize() to turn characters into tokens step_text_normalization() to perform text normalization.

Other Steps for Numeric Variables From Tokens: step_lda(), step_tf(), step_tfidf(), step_word_embeddings()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_tokenfilter(medium, max_tokens = 10) |>
  step_texthash(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, tate_text)

tidy(tate_rec, number = 3)
tidy(tate_obj, number = 3)

Description

step_tf() creates a specification of a recipe step that will convert a token variable into multiple variables containing the token counts.

Usage

step_tf(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  weight_scheme = "raw count",
  weight = 0.5,
  vocabulary = NULL,
  res = NULL,
  prefix = "tf",
  sparse = "auto",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("tf")
)

Arguments

Details

It is strongly advised to use step_tokenfilter before using step_tf to limit the number of variables created, otherwise you might run into memory issues. A good strategy is to start with a low token count and go up according to how much RAM you want to use.

Term frequency is a weight of how many times each token appears in each observation. There are different ways to calculate the weight and this step can do it in a couple of ways. Setting the argument weight_scheme to "binary" will result in a set of binary variables denoting if a token is present in the observation. "raw count" will count the times a token is present in the observation. "term frequency" will divide the count by the total number of in-vocabulary tokens in the document to limit the effect of the document length as longer documents tends to have the word present more times but not necessarily at a higher percentage. "log normalization" takes the log of 1 plus the count, adding 1 is done to avoid taking log of 0. Finally "double normalization" is the raw frequency divided by the raw frequency of the most occurring term in the document. This is then multiplied by weight and weight is added to the result. This is again done to prevent a bias towards longer documents.

The new columns will have names that begin with prefix, then the name of the variable, then the token, all separated by ⁠_⁠. For example, with the default prefix = "tf", a variable named text, and the token "word", the new column will be named tf_text_word.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, value, and id:

terms

character, the selectors or variables selected

value

character, the weighting scheme

id

character, id of this step

Tuning Parameters

This step has 2 tuning parameters:

• weight_scheme: Term Frequency Weight Method (type: character, default: raw count)

• weight: Weight (type: double, default: 0.5)

Sparse data

This step produces sparse columns if sparse = "yes" is being set. The default value "auto" won't trigger production of sparse columns if a recipe is recipes::prep()ed, but allows for a workflow to toggle to "yes" or "no" depending on whether the model supports recipes::sparse_data and if the model is expected to run faster with the data.

The mechanism for determining how much sparsity is produced isn't perfect, and there will be times when you want to manually overwrite by setting sparse = "yes" or sparse = "no".

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Numeric Variables From Tokens: step_lda(), step_texthash(), step_tfidf(), step_word_embeddings()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_tf(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, tate_text)

tidy(tate_rec, number = 2)
tidy(tate_obj, number = 2)

Description

step_tfidf() creates a specification of a recipe step that will convert a token variable into multiple variables containing the term frequency-inverse document frequency of tokens.

Usage

step_tfidf(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  vocabulary = NULL,
  res = NULL,
  smooth_idf = TRUE,
  norm = "l1",
  sublinear_tf = FALSE,
  prefix = "tfidf",
  sparse = "auto",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("tfidf")
)

Arguments

Details

It is strongly advised to use step_tokenfilter before using step_tfidf to limit the number of variables created; otherwise you may run into memory issues. A good strategy is to start with a low token count and increase depending on how much RAM you want to use.

Term frequency-inverse document frequency is the product of two statistics: the term frequency (TF) and the inverse document frequency (IDF).

Term frequency measures how many times each token appears in each observation.

Inverse document frequency is a measure of how informative a word is, e.g., how common or rare the word is across all the observations. If a word appears in all the observations it might not give that much insight, but if it only appears in some it might help differentiate between observations.

The IDF is defined as follows when smooth_idf = TRUE: idf = log(1 + (# documents in the corpus) / (# documents where the term appears)). When smooth_idf = FALSE the ⁠1 +⁠ is dropped.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, token, weight, and id:

terms

character, the selectors or variables selected

token

character, name of token

weight

numeric, the calculated IDF weight

id

character, id of this step

The new columns will have names that begin with prefix, then the name of the variable, then the token, all separated by ⁠_⁠. For example, with the default prefix = "tfidf", a variable named text, and the token "word", the new column will be named tfidf_text_word.

Sparse data

This step produces sparse columns if sparse = "yes" is being set. The default value "auto" won't trigger production of sparse columns if a recipe is recipes::prep()ed, but allows for a workflow to toggle to "yes" or "no" depending on whether the model supports recipes::sparse_data and if the model is expected to run faster with the data.

The mechanism for determining how much sparsity is produced isn't perfect, and there will be times when you want to manually overwrite by setting sparse = "yes" or sparse = "no".

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Numeric Variables From Tokens: step_lda(), step_texthash(), step_tf(), step_word_embeddings()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_tfidf(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, tate_text)

tidy(tate_rec, number = 2)
tidy(tate_obj, number = 2)

Description

step_tokenfilter() creates a specification of a recipe step that will convert a token variable to be filtered based on frequency.

Usage

step_tokenfilter(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  max_times = Inf,
  min_times = 0,
  percentage = FALSE,
  max_tokens = 100,
  filter_fun = NULL,
  res = NULL,
  skip = FALSE,
  id = rand_id("tokenfilter")
)

Arguments

Details

This step allows you to limit the tokens you are looking at by filtering on their occurrence in the corpus. You are able to exclude tokens if they appear too many times or too few times in the data. It can be specified as counts using max_times and min_times or as percentages by setting percentage as TRUE. In addition one can filter to only use the top max_tokens used tokens. If max_tokens is set to Inf then all the tokens will be used. This will generally lead to very large data sets when then tokens are words or trigrams. A good strategy is to start with a low token count and go up according to how much RAM you want to use.

It is strongly advised to filter before using step_tf or step_tfidf to limit the number of variables created.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, value, and id:

terms

character, the selectors or variables selected

value

integer, number of unique tokens

id

character, id of this step

Tuning Parameters

This step has 3 tuning parameters:

• max_times: Maximum Token Frequency (type: integer, default: Inf)

• min_times: Minimum Token Frequency (type: integer, default: 0)

• max_tokens: # Retained Tokens (type: integer, default: 100)

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Token Modification: step_lemma(), step_ngram(), step_pos_filter(), step_stem(), step_stopwords(), step_tokenmerge()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_tokenfilter(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

tidy(tate_rec, number = 2)
tidy(tate_obj, number = 2)

Description

step_tokenize() creates a specification of a recipe step that will convert a character predictor into a token variable.

Usage

step_tokenize(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  training_options = list(),
  options = list(),
  token = "words",
  engine = "tokenizers",
  custom_token = NULL,
  skip = FALSE,
  id = rand_id("tokenize")
)

Arguments

Details

options(width = 55)

Tokenization is the act of splitting a character vector into smaller parts to be further analyzed. This step uses the tokenizers package which includes heuristics on how to to split the text into paragraphs tokens, word tokens, among others. textrecipes keeps the tokens as a token variable and other steps will do their tasks on those token variables before transforming them back to numeric variables.

Working with textrecipes will almost always start by calling step_tokenize followed by modifying and filtering steps. This is not always the case as you sometimes want to apply pre-tokenization steps; this can be done with recipes::step_mutate().

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Engines

The choice of engine determines the possible choices of token.

The following is some small example data used in the following examples

text_tibble <- tibble(
  text = c("This is words", "They are nice!")
)

tokenizers

The tokenizers package is the default engine and it comes with the following unit of token. All of these options correspond to a function in the tokenizers package.

• "words" (default)

• "characters"

• "character_shingles"

• "ngrams"

• "skip_ngrams"

• "sentences"

• "lines"

• "paragraphs"

• "regex"

• "ptb" (Penn Treebank)

• "skip_ngrams"

• "word_stems"

The default tokenizer is "word" which splits the text into a series of words. By using step_tokenize() without setting any arguments you get word tokens

recipe(~ text, data = text_tibble) |>
  step_tokenize(text) |>
  show_tokens(text, n = 2)

This tokenizer has arguments that change how the tokenization occurs and can accessed using the options argument by passing a named list. Here we are telling tokenizers::tokenize_words that we don't want to turn the words to lowercase

recipe(~ text, data = text_tibble) |>
  step_tokenize(text,
                options = list(lowercase = FALSE)) |>
  show_tokens(text, n = 2)

We can also stop removing punctuation.

recipe(~ text, data = text_tibble) |>
  step_tokenize(text,
                options = list(strip_punct = FALSE,
                               lowercase = FALSE)) |>
  show_tokens(text, n = 2)

The tokenizer can be changed by setting a different token. Here we change it to return character tokens.

recipe(~ text, data = text_tibble) |>
  step_tokenize(text, token = "characters") |>
  show_tokens(text, n = 2)

It is worth noting that not all these token methods are appropriate but are included for completeness.

spacyr

• "words"

tokenizers.bpe

The tokeenizers.bpe engine performs Byte Pair Encoding Text Tokenization.

• "words"

This tokenizer is trained on the training set and will thus need to be passed training arguments. These are passed to the training_options argument and the most important one is vocab_size. The determines the number of unique tokens the tokenizer will produce. It is generally set to a much higher value, typically in the thousands, but is set to 22 here for demonstration purposes.

recipe(~ text, data = text_tibble) |>
  step_tokenize(
    text,
    engine = "tokenizers.bpe",
    training_options = list(vocab_size = 22)
  ) |>
  show_tokens(text, n = 2)

recipe(~ text, data = text_tibble) |>
  step_tokenize(
    text,
    engine = "tokenizers.bpe",
    training_options = list(vocab_size = 22)
  ) |>
  show_tokens(text, n = 2) |>
  lapply(function(x) gsub("▁", "_", x))

udpipe

• "words"

The udpipe engine requires a pre-trained udpipe model. Load one with udpipe::udpipe_load_model() (use udpipe::udpipe_download_model() to download one first) and pass it as the model element of the training_options argument.

model <- udpipe::udpipe_load_model("english-ewt-ud-2.5-191206.udpipe")

recipe(~ text, data = text_tibble) |>
  step_tokenize(
    text,
    engine = "udpipe",
    training_options = list(model = model)
  )

custom_token

Sometimes you need to perform tokenization that is not covered by the supported engines. In that case you can use the custom_token argument to pass a function in that performs the tokenization you want.

Below is an example of a very simple space tokenization. This is a very fast way of tokenizing.

space_tokenizer <- function(x) {
  strsplit(x, " +")
}

recipe(~ text, data = text_tibble) |>
  step_tokenize(
    text,
    custom_token = space_tokenizer
  ) |>
  show_tokens(text, n = 2)

Tidying

When you tidy() this step, a tibble is returned with columns terms, value, and id:

terms

character, the selectors or variables selected

value

character, unit of tokenization

id

character, id of this step

step <- "step_tokenize"
result <- knitr::knit_child("man/rmd/tunable-args.Rmd")
cat(result)

Case weights

The underlying operation does not allow for case weights.

See Also

step_untokenize() to untokenize.

Other Steps for Tokenization: step_tokenize_bpe(), step_tokenize_sentencepiece(), step_tokenize_wordpiece()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

tidy(tate_rec, number = 1)
tidy(tate_obj, number = 1)

tate_obj_chars <- recipe(~., data = tate_text) |>
  step_tokenize(medium, token = "characters") |>
  prep()

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

Description

step_tokenize_bpe() creates a specification of a recipe step that will convert a character predictor into a token variable using Byte Pair Encoding.

Usage

step_tokenize_bpe(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  vocabulary_size = 1000,
  options = list(),
  res = NULL,
  skip = FALSE,
  id = rand_id("tokenize_bpe")
)

Arguments

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms and id:

terms

character, the selectors or variables selected

id

character, id of this step

Tuning Parameters

This step has 1 tuning parameters:

• vocabulary_size: # Unique Tokens in Vocabulary (type: integer, default: 1000)

Case weights

The underlying operation does not allow for case weights.

See Also

step_untokenize() to untokenize.

Other Steps for Tokenization: step_tokenize(), step_tokenize_sentencepiece(), step_tokenize_wordpiece()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize_bpe(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

tidy(tate_rec, number = 1)
tidy(tate_obj, number = 1)

Description

step_tokenize_sentencepiece() creates a specification of a recipe step that will convert a character predictor into a token variable using SentencePiece tokenization.

Usage

step_tokenize_sentencepiece(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  vocabulary_size = 1000,
  model = NULL,
  options = list(),
  res = NULL,
  skip = FALSE,
  id = rand_id("tokenize_sentencepiece")
)

Arguments

Details

If you are running into errors, you can investigate the progress of the compiled code by setting options = list(verbose = TRUE). This can reveal if sentencepiece ran correctly or not.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms and id:

terms

character, the selectors or variables selected

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_untokenize() to untokenize.

Other Steps for Tokenization: step_tokenize(), step_tokenize_bpe(), step_tokenize_wordpiece()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize_sentencepiece(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

tidy(tate_rec, number = 1)
tidy(tate_obj, number = 1)

# Using a pretrained model
model_dir <- tempfile()
dir.create(model_dir)
file <- tempfile(tmpdir = model_dir)
writeLines(as.character(tate_text$medium), file)
trained <- sentencepiece::sentencepiece(
  file,
  vocab_size = 100,
  model_dir = model_dir
)

recipe(~., data = tate_text) |>
  step_tokenize_sentencepiece(medium, model = trained$model_path) |>
  prep() |>
  bake(new_data = NULL, medium) |>
  slice(1:2)

Description

step_tokenize_wordpiece() creates a specification of a recipe step that will convert a character predictor into a token variable using WordPiece tokenization.

Usage

step_tokenize_wordpiece(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  vocab = wordpiece::wordpiece_vocab(),
  unk_token = "[UNK]",
  max_chars = 100,
  skip = FALSE,
  id = rand_id("tokenize_wordpiece")
)

Arguments

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms and id:

terms

character, the selectors or variables selected

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_untokenize() to untokenize.

Other Steps for Tokenization: step_tokenize(), step_tokenize_bpe(), step_tokenize_sentencepiece()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize_wordpiece(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

tidy(tate_rec, number = 1)
tidy(tate_obj, number = 1)

Description

step_tokenmerge() creates a specification of a recipe step that will take multiple token variables and combine them into one token variable.

Usage

step_tokenmerge(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  prefix = "tokenmerge",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("tokenmerge")
)

Arguments

Details

All the selected variables are merged into a single new variable named prefix, which is "tokenmerge" by default. The name of the selected variables is not part of the new name.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms and id:

terms

character, the selectors or variables selected

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Token Modification: step_lemma(), step_ngram(), step_pos_filter(), step_stem(), step_stopwords(), step_tokenfilter()

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium, artist) |>
  step_tokenmerge(medium, artist)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL)

tidy(tate_rec, number = 2)
tidy(tate_obj, number = 2)

Description

step_untokenize() creates a specification of a recipe step that will convert a token variable into a character predictor.

Usage

step_untokenize(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  sep = " ",
  skip = FALSE,
  id = rand_id("untokenize")
)

Arguments

Details

This steps will turn a token vector back into a character vector. This step is calling paste internally to put the tokens back together to a character.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, value, and id:

terms

character, the selectors or variables selected

value

character, seperator used for collapsing

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Examples

library(recipes)
library(modeldata)
data(tate_text)

tate_rec <- recipe(~., data = tate_text) |>
  step_tokenize(medium) |>
  step_untokenize(medium)

tate_obj <- tate_rec |>
  prep()

bake(tate_obj, new_data = NULL, medium) |>
  slice(1:2)

bake(tate_obj, new_data = NULL) |>
  slice(2) |>
  pull(medium)

tidy(tate_rec, number = 2)
tidy(tate_obj, number = 2)

Description

step_word_embeddings() creates a specification of a recipe step that will convert a token variable into word-embedding dimensions by aggregating the vectors of each token from a pre-trained embedding.

Usage

step_word_embeddings(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  columns = NULL,
  embeddings,
  aggregation = c("sum", "mean", "min", "max"),
  aggregation_default = 0,
  prefix = "wordembed",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("word_embeddings")
)

Arguments

Details

Word embeddings map words (or other tokens) into a high-dimensional feature space. This function maps pre-trained word embeddings onto the tokens in your data.

The argument embeddings provides the pre-trained vectors. Each dimension present in this tibble becomes a new feature column, with each column aggregated across each row of your text using the function supplied in the aggregation argument.

The new components will have names that begin with prefix, then the name of the variable being embedded, then the name of the variable from the embeddings tibble (usually something like "d7"). For example, using the default "wordembed" prefix, a variable named text, and the GloVe embeddings from the textdata package (where the column names are d1, d2, etc), new columns would be wordembed_text_d1, wordembed_text_d2, etc.

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any).

Tidying

When you tidy() this step, a tibble is returned with columns terms, embedding_rows, aggregation, and id:

terms

character, the selectors or variables selected

embedding_rows

integer, number of rows in embedding

aggregation

character,aggregation

id

character, id of this step

Case weights

The underlying operation does not allow for case weights.

See Also

step_tokenize() to turn characters into tokens

Other Steps for Numeric Variables From Tokens: step_lda(), step_texthash(), step_tf(), step_tfidf()

Examples

library(recipes)

embeddings <- tibble(
  tokens = c("the", "cat", "ran"),
  d1 = c(1, 0, 0),
  d2 = c(0, 1, 0),
  d3 = c(0, 0, 1)
)

sample_data <- tibble(
  text = c(
    "The.",
    "The cat.",
    "The cat ran."
  ),
  text_label = c("fragment", "fragment", "sentence")
)

rec <- recipe(text_label ~ ., data = sample_data) |>
  step_tokenize(text) |>
  step_word_embeddings(text, embeddings = embeddings)

obj <- rec |>
  prep()

bake(obj, sample_data)

tidy(rec, number = 2)
tidy(obj, number = 2)

Description

A tokenlist object is a thin wrapper around a list of character vectors, with a few attributes.

Usage

tokenlist(tokens = list(), lemma = NULL, pos = NULL)

Arguments

Value

a tokenlist object.

Examples

abc <- list(letters, LETTERS)
tokenlist(abc)

unclass(tokenlist(abc))

tibble(text = tokenlist(abc))

library(tokenizers)
library(modeldata)
data(tate_text)
tokens <- tokenize_words(as.character(tate_text$medium))

tokenlist(tokens)