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\name{CoNLLTextDocument}
\alias{CoNLLTextDocument}
\title{CoNLL-Style Text Documents}
\description{
Create text documents from CoNLL-style files.
}
\usage{
CoNLLTextDocument(con, encoding = "unknown", meta = list())
}
\arguments{
\item{con}{a connection object or a character string.
See \code{\link{scan}()} for details.
}
\item{encoding}{encoding to be assumed for input strings.
See \code{\link{scan}()} for details.
}
\item{meta}{a named or empty list of document metadata tag-value
pairs.}
}
\details{
CoNLL-style files use an extended tabular format where empty lines
separate sentences, and non-empty lines consist of whitespace
separated columns giving the word tokens and annotations for these.
In principle, these annotations can vary from corpus to corpus: the
current version of \code{CoNLLTextDocument()} assumes a fixed set of 3
columns giving, respectively, the word token and its POS and chunk
tags.
The lines are read from the given connection and split into fields
using \code{\link{scan}()}. From this, a suitable representation of
the provided information is obtained, and returned as a CoNLL text
document object inheriting from classes \code{"CoNLLTextDocument"} and
\code{"\link{TextDocument}"}.
There are methods for generics
\code{\link{words}()},
\code{\link{sents}()},
\code{\link{tagged_words}()},
\code{\link{tagged_sents}()}, and
\code{\link{chunked_sents}()}
(as well as \code{\link{as.character}()})
and class \code{"CoNLLTextDocument"},
which should be used to access the text in such text document
objects.
The methods for generics
\code{\link{tagged_words}()} and
\code{\link{tagged_sents}()}
provide a mechanism for mapping POS tags via the \code{map} argument,
see section \bold{Details} in the help page for
\code{\link{tagged_words}()} for more information.
The POS tagset used will be inferred from the \code{POS_tagset}
metadata element of the CoNLL-style text document.
}
\value{
An object inheriting from \code{"CoNLLTextDocument"} and
\code{"\link{TextDocument}"}.
}
\seealso{
\code{\link{TextDocument}} for basic information on the text document
infrastructure employed by package \pkg{NLP}.
\url{http://ifarm.nl/signll/conll/} for general information about
CoNLL (Conference on Natural Language Learning), the yearly meeting of
the Special Interest Group on Natural Language Learning of the
Association for Computational Linguistics.
\url{http://www.cnts.ua.ac.be/conll2000/chunking/} for the CoNLL 2000
chunking task, and training and test data sets which can be read in
using \code{CoNLLTextDocument()}.
}
|
