R: Read In a Text Document

readTabular {tm}

R Documentation

Read In a Text Document

Description

Return a function which reads in a text document from a tabular data structure (like a data frame or a list matrix) with knowledge about its internal structure and possible available metadata as specified by a so-called mapping.

Usage

readTabular(mapping)

Arguments

mapping

A named list of characters. The constructed reader will map each character entry to the content or meta datum of the text document as specified by the named list entry. Valid names include Content to access the document's content, any valid attribute name, and characters which are mapped to LocalMetaData entries.

Details

Formally this function is a function generator, i.e., it returns a function (which reads in a text document) with a well-defined signature, but can access passed over arguments (e.g., the mapping) via lexical scoping.

Value

A function with the signature elem, language, id:

elem: a list with the named component content which must hold the document to be read in.
language: a string giving the text's language.
id: a unique identification string for the returned text document.

The function returns a PlainTextDocument representing the text and meta data extracted from elem$content.

Author(s)

Ingo Feinerer

Examples

df <- data.frame(contents = c("content 1", "content 2", "content 3"),
                 title    = c("title 1"  , "title 2"  , "title 3"  ),
                 authors  = c("author 1" , "author 2" , "author 3" ),
                 topics   = c("topic 1"  , "topic 2"  , "topic 3"  ),
                 stringsAsFactors = FALSE)
m <- list(Content = "contents", Heading = "title",
          Author = "authors", Topic = "topics")
myReader <- readTabular(mapping = m)
ds <- DataframeSource(df)
elem <- getElem(stepNext(ds))
(result <- myReader(elem, language = "en", id = "id1"))
meta(result)

[Package tm version 0.5-10 Index]