Pattern(s) for use in matching Feature, tokens, and keywords through a valuetype pattern.
a character vector, list of character vectors, dictionary, or collocations object. See pattern for details.
pattern argument is a vector of patterns, including sequences,
to match in a target object, whose match type is specified by
Note that an empty pattern (
"") will match "padding" in a tokens object.
A character vector of token patterns to be selected or removed.
Whitespace is not privileged, so that in a character vector, white space is interpreted
literally. If you wish to consider whitespace-separated elements as sequences of tokens,
wrap the argument in
list of character objects
If the list elements are character vectors of
length 1, then this is equivalent to a vector of characters. If a list element contains
a vector of characters longer than length 1, then for matching will consider these
as sequences of matches, equivalent to wrapping the argument in
except for matching to dfm features where this does not apply.
Values in dictionary are used as patterns, for literal matches.
Multi-word values are automatically converted into phrases, so performing selection or
compounding using a dictionary is the same as wrapping the dictionary in
Collocations objects created from
which are treated as phrases automatically.
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# these are interpreted literally (patt1 <- c("president", "white house", "house of representatives")) # as multi-word sequences phrase(patt1) # three single-word patterns (patt2 <- c("president", "white_house", "house_of_representatives")) phrase(patt2) # this is equivalent to phrase(patt1) (patt3 <- list(c("president"), c("white", "house"), c("house", "of", "representatives"))) # glob expression can be used phrase(patt4 <- c("president?", "white house", "house * representatives")) # this is equivalent to phrase(patt4) (patt5 <- list(c("president?"), c("white", "house"), c("house", "*", "representatives"))) # dictionary with multi-word matches (dict1 <- dictionary(list(us = c("president", "white house", "house of representatives")))) phrase(dict1)
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