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Combine documents in corpus by a grouping variable

Source: R/corpus_group.R
corpus_group.Rd

Combine documents in a corpus object by a grouping variable, by concatenating their texts in the order of the documents within each grouping variable.

Usage

corpus_group(x, groups = docid(x), fill = FALSE, concatenator = " ")

Arguments

x

corpus object

groups

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.

fill

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.

concatenator

the concatenation character that will connect the grouped documents.

Value

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.

Examples

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 :
#> ""
#>