Combine documents in a corpus object by a grouping variable, by concatenating their texts in the order of the documents within each grouping variable.
corpus_group(x, groups = docid(x), fill = FALSE, concatenator = " ")corpus 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.
the concatenation character that will connect the grouped documents.
a corpus object whose documents are equal to the unique group combinations, and whose texts are the concatenations of the texts 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")))
corpus_group(corp, groups = grp)
#> Corpus consisting of 2 documents and 1 docvar.
#> grp1 :
#> "a a b a b c c"
#>
#> grp2 :
#> "a c d d a c c d"
#>
corpus_group(corp, groups = c(1, 1, 2, 2))
#> Corpus consisting of 2 documents and 1 docvar.
#> 1 :
#> "a a b a b c c"
#>
#> 2 :
#> "a c d d a c c d"
#>
corpus_group(corp, groups = factor(c(1, 1, 2, 2), levels = 1:3))
#> Corpus consisting of 2 documents and 1 docvar.
#> 1 :
#> "a a b a b c c"
#>
#> 2 :
#> "a c d d a c c d"
#>
# with fill
corpus_group(corp, groups = factor(c(1, 1, 2, 2), levels = 1:3), fill = TRUE)
#> Corpus consisting of 3 documents and 1 docvar.
#> 1 :
#> "a a b a b c c"
#>
#> 2 :
#> "a c d d a c c d"
#>
#> 3 :
#> ""
#>