threads {tm.plugin.mail}

E-Mail Threads

Description

Extract threads (i.e., chains of messages on a single subject) from e-mail documents.

Usage

threads(x)

Arguments

x

A corpus consisting of e-mails (MailDocuments).

Details

This function uses a one-pass algorithm for extracting the thread information by inspecting the “References” header. Some mails (e.g., reply mails appearing before their corresponding base mails) might not be tagged correctly.

Value

A list with the two named components ThreadID and ThreadDepth, listing a thread and the level of replies for each mail in the corpus x.

Examples

require("tm")
newsgroup <- system.file("mails", package = "tm.plugin.mail")
news <- VCorpus(DirSource(newsgroup),
                readerControl = list(reader = readMail))
vapply(news, meta, "id", FUN.VALUE = "")
lapply(news, function(x) meta(x, "header")$References)
(info <- threads(news))
lengths(split(news, info$ThreadID))