R/tokens_group.R
tokens_group.RdCombine documents in a tokens object by a grouping variable, by concatenating the tokens in the order of the documents within each grouping variable.
tokens_group(x, groups = docid(x), fill = FALSE, env = NULL)tokens object
grouping variable for sampling, equal in length to the number
of documents. This will be evaluated in the docvars data.frame, so that
docvars may be referred to by name without quoting. This also changes
previous behaviours for groups. See news(Version >= "3.0", package = "quanteda") for details.
logical; if TRUE and groups is a factor, then use all levels
of the factor when forming the new documents of the grouped object. This
will result in a new "document" with empty content for levels not observed,
but for which an empty document may be needed. If groups is a factor of
dates, for instance, then fill = TRUE ensures that the new object will
consist of one new "document" by date, regardless of whether any documents
previously existed with that date. Has no effect if the groups
variable(s) are not factors.
an environment or a list object in which x is searched.
Passed to substitute for non-standard evaluation.
a tokens object whose documents are equal to the unique group combinations, and whose tokens are the concatenations of the tokens by group. Document-level variables that have no variation within groups are saved in docvars. Document-level variables that are lists are dropped from grouping, even when these exhibit no variation within groups.
corp <- corpus(c("a a b", "a b c c", "a c d d", "a c c d"),
docvars = data.frame(grp = c("grp1", "grp1", "grp2", "grp2")))
toks <- tokens(corp)
tokens_group(toks, groups = grp)
#> Tokens consisting of 2 documents and 1 docvar.
#> grp1 :
#> [1] "a" "a" "b" "a" "b" "c" "c"
#>
#> grp2 :
#> [1] "a" "c" "d" "d" "a" "c" "c" "d"
#>
tokens_group(toks, groups = c(1, 1, 2, 2))
#> Tokens consisting of 2 documents and 1 docvar.
#> 1 :
#> [1] "a" "a" "b" "a" "b" "c" "c"
#>
#> 2 :
#> [1] "a" "c" "d" "d" "a" "c" "c" "d"
#>
# with fill
tokens_group(toks, groups = factor(c(1, 1, 2, 2), levels = 1:3))
#> Tokens consisting of 2 documents and 1 docvar.
#> 1 :
#> [1] "a" "a" "b" "a" "b" "c" "c"
#>
#> 2 :
#> [1] "a" "c" "d" "d" "a" "c" "c" "d"
#>
tokens_group(toks, groups = factor(c(1, 1, 2, 2), levels = 1:3), fill = TRUE)
#> Tokens consisting of 3 documents and 1 docvar.
#> 1 :
#> [1] "a" "a" "b" "a" "b" "c" "c"
#>
#> 2 :
#> [1] "a" "c" "d" "d" "a" "c" "c" "d"
#>
#> 3 :
#> character(0)
#>