quanteda (version 0.99)

tokens_recompile: recompile a hashed tokens object

Description

This function recompiles a hashed tokens object when the vocabulary has been changed in a way that makes some of its types identical, such as lowercasing when a lowercased version of the type already exists in the hash table, or introduces gaps in the integer map of the types. It also reindexes the types atttribute to account for types that may have become duplicates, through a procedure such as stemming or lowercasing; or the addition of new tokens through compounding.

Usage

tokens_recompile(x, method = c("C++", "R"))

Arguments

x

the tokens object to be recompiled

method

"C++" for C++ implementation or "R" for an older R-based method

Examples

# NOT RUN {
# lowercasing
toks1 <- tokens(c(one = "a b c d A B C D",
                 two = "A B C d"))
attr(toks1, "types") <- char_tolower(attr(toks1, "types"))
unclass(toks1)
unclass(quanteda:::tokens_recompile(toks1))

# stemming
toks2 <- tokens("Stemming stemmed many word stems.")
unclass(toks2)
unclass(quanteda:::tokens_recompile(tokens_wordstem(toks2)))

# compounding
toks3 <- tokens("One two three four.")
unclass(toks3)
unclass(tokens_compound(toks3, "two three"))

# lookup
dict <- dictionary(list(test = c("one", "three")))
unclass(tokens_lookup(toks3, dict))

# empty pads
unclass(tokens_select(toks3, dict))
unclass(tokens_select(toks3, dict, pad = TRUE))

# ngrams
unclass(tokens_ngrams(toks3, n = 2:3))

# }