R: Readers

Reader {tm} | R Documentation

## Readers

### Description

Creating readers.

### Usage

    getReaders()

### Details

Readers are functions for extracting textual content and metadata out of elements delivered by a `Source`, and for constructing a `TextDocument`. A reader must accept following arguments in its signature:

`elem`

  a named list with the components `content` and `uri` (as delivered by a `Source` via `getElem` or `pGetElem`).

`language`

  a character string giving the language.

`id`

  a character giving a unique identifier for the created text document.

The element `elem` is typically provided by a source whereas the language and the identifier are normally provided by a corpus constructor (for the case that `elem$content` does not give information on these two essential items).

In case a reader expects configuration arguments we can use a function generator. A function generator is indicated by inheriting from class `FunctionGenerator` and `function`. It allows us to process additional arguments, store them in an environment, return a reader function with the well-defined signature described above, and still be able to access the additional arguments via lexical scoping. All corpus constructors in package tm check the reader function for being a function generator and if so apply it to yield the reader with the expected signature.

### Value

For `getReaders()`, a character vector with readers provided by package tm.

### See Also

`readDOC`, `readPDF`, `readPlain`, `readRCV1`, `readRCV1asPlain`, `readReut21578XML`, `readReut21578XMLasPlain`, and `readXML`.

[Package tm version 0.7-8 Index]