R: Corpora

Corpus {tm} | R Documentation

## Corpora

### Description

Representing and computing on corpora.

### Details

Corpora are collections of documents containing (natural language) text. In packages which employ the infrastructure provided by package tm, such corpora are represented via the virtual S3 class `Corpus`: such packages then provide S3 corpus classes extending the virtual base class (such as `VCorpus` provided by package tm itself).

All extension classes must provide accessors to extract subsets (`[`), individual documents (`[[`), and metadata (`meta`). The function `length` must return the number of documents, and `as.list` must construct a list holding the documents.

A corpus can have two types of metadata (accessible via `meta`). Corpus metadata contains corpus specific metadata in form of tag-value pairs. Document level metadata contains document specific metadata but is stored in the corpus as a data frame. Document level metadata is typically used for semantic reasons (e.g., classifications of documents form an own entity due to some high-level information like the range of possible values) or for performance reasons (single access instead of extracting metadata of each document).

The function `Corpus` is a convenience alias to `SimpleCorpus` or `VCorpus`, depending on the arguments provided.

### See Also

`SimpleCorpus`, `VCorpus`, and `PCorpus` for the corpora classes provided by package tm.

`DCorpus` for a distributed corpus class provided by package tm.plugin.dc.

[Package tm version 0.7-1 Index]