require(quanteda)
Using corpus_segment(), you can extract segments of texts and tags from documents. This is particularly useful when you analyze sections of documents or transcripts separately.
corp_tagged <- corpus(c("##INTRO This is the introduction.
##DOC1 This is the first document. Second sentence in Doc 1.
##DOC3 Third document starts here. End of third document.",
"##INTRO Document ##NUMBER Two starts before ##NUMBER Three."))
corp_sect <- corpus_segment(corp_tagged, pattern = "##*")
cbind(docvars(corp_sect), text = as.character(corp_sect))
## pattern text
## text1.1 ##INTRO This is the introduction.
## text1.2 ##DOC1 This is the first document. Second sentence in Doc 1.
## text1.3 ##DOC3 Third document starts here. End of third document.
## text2.1 ##INTRO Document
## text2.2 ##NUMBER Two starts before
## text2.3 ##NUMBER Three.
corp_speeches <- corpus("Mr. Smith: Text.
Mrs. Jones: More text.
Mr. Smith: I'm speaking, again.")
corp_speakers <- corpus_segment(corp_speeches, pattern = "\\b[A-Z].+\\s[A-Z][a-z]+:", valuetype = "regex")
cbind(docvars(corp_speakers), text = as.character(corp_speakers))
## pattern text
## text1.1 Mr. Smith: Text.
## text1.2 Mrs. Jones: More text.
## text1.3 Mr. Smith: I'm speaking, again.
You should use corpus_reshape() to split documents into sentences, but you can do similar operations using corpus_segment() by setting pattern_position = "after".
corp <- corpus(c(d1 = "This, is a sentence? You: come here.",
d2 = "Yes, yes okay."))
corp_sent <- corpus_segment(corp, pattern = "\\p{P}", valuetype = "regex",
extract_pattern = FALSE, pattern_position = "after")
print(corp_sent)
## Corpus consisting of 6 documents.
## d1.1 :
## "This,"
##
## d1.2 :
## "is a sentence?"
##
## d1.3 :
## "You:"
##
## d1.4 :
## "come here."
##
## d2.1 :
## "Yes,"
##
## d2.2 :
## "yes okay."