"Compresses" or groups a dfm or fcm whose dimension names are
the same, for either documents or features. This may happen, for instance,
if features are made equivalent through application of a thesaurus. It could also be needed after a
cbind.dfm or rbind.dfm operation. In most cases, you will not
need to call `dfm_compress`, since it is called automatically by functions that change the
dimensions of the dfm, e.g. dfm_tolower.
dfm_compress(x, margin = c("both", "documents", "features"))fcm_compress(x)
character indicating on which margin to compress a dfm, either
"documents", "features", or "both" (default). For fcm
objects, "documents" has no effect.
additional arguments passed from generic to specific methods
dfm_compress returns a dfm whose dimensions have been
recombined by summing the cells across identical dimension names
(docnames or featnames). The docvars will be
preserved for combining by features but not when documents are combined.
fcm_compress returns an fcm whose features have been
recombined by combining counts of identical features, summing their counts.
# NOT RUN {
# dfm_compress examples
mat <- rbind(dfm(c("b A A", "C C a b B"), tolower = FALSE),
dfm("A C C C C C", tolower = FALSE))
colnames(mat) <- char_tolower(featnames(mat))
mat
dfm_compress(mat, margin = "documents")
dfm_compress(mat, margin = "features")
dfm_compress(mat)
# no effect if no compression needed
compactdfm <- dfm(data_corpus_inaugural[1:5])
dim(compactdfm)
dim(dfm_compress(compactdfm))
# compress an fcm
myfcm <- fcm(tokens("A D a C E a d F e B A C E D"),
context = "window", window = 3)
## this will produce an error:
# fcm_compress(myfcm)
txt <- c("The fox JUMPED over the dog.",
"The dog jumped over the fox.")
toks <- tokens(txt, remove_punct = TRUE)
myfcm <- fcm(toks, context = "document")
colnames(myfcm) <- rownames(myfcm) <- tolower(colnames(myfcm))
colnames(myfcm)[5] <- rownames(myfcm)[5] <- "fox"
myfcm
fcm_compress(myfcm)
# }
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