dictionary-class: create a dictionary

Description

Create a quanteda dictionary, either from a list or by importing from a foreign format. Currently supported formats are the Wordstat and LIWC formats.

Usage

dictionary(x = NULL, file = NULL, format = NULL, enc = "",
  tolower = TRUE, maxcats = 10)

Arguments

a list of character vector dictionary entries, including regular expressions (see examples)

file

file identifier for a foreign dictionary

format

character identifier for the format of the foreign dictionary. Available options are: [object Object],[object Object]

enc

optional encoding value for dictionaries imported in Wordstat format

tolower

if TRUE, convert all dictionary functions to lower

maxcats

optional maximum categories to which a word could belong in a LIWC dictionary file, defaults to 10 (which is more than the actual LIWC 2007 dictionary uses). The default value of 10 is likely to be more than enough.

Value

A list with a ductionary class label, to be used by other functions in quanteda.

References

Wordstat dictionaries page, from Provalis Research http://provalisresearch.com/products/content-analysis-software/wordstat-dictionary/.

Pennebaker, J.W., Chung, C.K., Ireland, M., Gonzales, A., & Booth, R.J. (2007). The development and psychometric properties of LIWC2007. [Software manual]. Austin, TX (www.liwc.net).

Examples

Run this code

mycorpus <- subset(inaugCorpus, Year>1900)
mydict <-
    dictionary(list(christmas=c("Christmas", "Santa", "holiday"),
                    opposition=c("Opposition", "reject", "notincorpus"),
                    taxing="taxing",
                    taxation="taxation",
                    taxregex="tax*",
                    country="united states"))
dfm(mycorpus, dictionary=mydict)
# import the Laver-Garry dictionary from http://bit.ly/1FH2nvf
lgdict <- dictionary(file="~/Dropbox/QUANTESS/dictionaries/Misc Provalis/LaverGarry.cat",
                     format="wordstat")
dfm(inaugTexts, dictionary=lgdict)

# import a LIWC formatted dictionary
liwcdict <- dictionary(file = "~/Dropbox/QUANTESS/dictionaries/LIWC/LIWC2001_English.dic",
                       format = "LIWC")
dfm(inaugTexts, dictionary=liwcdict)