Returns document subsets of a tokens that meet certain conditions, including direct logical operations on docvars (document-level variables). tokens_subset() functions identically to subset.data.frame(), using non-standard evaluation to evaluate conditions based on the docvars in the tokens.

tokens_subset(x, subset, drop_docid = TRUE, ...)

Arguments

x

tokens object to be subsetted

subset

logical expression indicating the documents to keep: missing values are taken as false

drop_docid

if TRUE, docid for documents are removed as the result of subsetting.

...

not used

Value

tokens object, with a subset of documents (and docvars) selected according to arguments

See also

Examples

corp <- corpus(c(d1 = "a b c d", d2 = "a a b e",
                 d3 = "b b c e", d4 = "e e f a b"),
                 docvars = data.frame(grp = c(1, 1, 2, 3)))
toks <- tokens(corp)
# selecting on a docvars condition
tokens_subset(toks, grp > 1)
#> Tokens consisting of 2 documents and 1 docvar.
#> d3 :
#> [1] "b" "b" "c" "e"
#> 
#> d4 :
#> [1] "e" "e" "f" "a" "b"
#> 
# selecting on a supplied vector
tokens_subset(toks, c(TRUE, FALSE, TRUE, FALSE))
#> Tokens consisting of 2 documents and 1 docvar.
#> d1 :
#> [1] "a" "b" "c" "d"
#> 
#> d3 :
#> [1] "b" "b" "c" "e"
#>