Description Usage Arguments Value Note Examples
"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()
.
1 2 3 | dfm_compress(x, margin = c("both", "documents", "features"))
fcm_compress(x)
|
x |
input object, a dfm or fcm |
margin |
character indicating on which margin to compress a dfm, either
|
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.
fcm_compress
works only when the fcm was created with a
document context.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | # dfm_compress examples
dfmat <- rbind(dfm(c("b A A", "C C a b B"), tolower = FALSE),
dfm("A C C C C C", tolower = FALSE))
colnames(dfmat) <- char_tolower(featnames(dfmat))
dfmat
dfm_compress(dfmat, margin = "documents")
dfm_compress(dfmat, margin = "features")
dfm_compress(dfmat)
# no effect if no compression needed
dfmatsubset <- dfm(data_corpus_inaugural[1:5])
dim(dfmatsubset)
dim(dfm_compress(dfmatsubset))
# compress an fcm
fcmat1 <- 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(fcmat1)
txt <- c("The fox JUMPED over the dog.",
"The dog jumped over the fox.")
toks <- tokens(txt, remove_punct = TRUE)
fcmat2 <- fcm(toks, context = "document")
colnames(fcmat2) <- rownames(fcmat2) <- tolower(colnames(fcmat2))
colnames(fcmat2)[5] <- rownames(fcmat2)[5] <- "fox"
fcmat2
fcm_compress(fcmat2)
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