dictionary: 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 reading in imported dictionaries. This uses the iconv labels for encoding. See the "Encoding" section of the help for file.

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 dictionary class object, essentially a specially classed named list of characters.

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="http://www.kenbenoit.net/courses/essex2014qta/LaverGarry.cat",
                     format="wordstat")
dfm(inaugTexts, dictionary=lgdict)

# import a LIWC formatted dictionary
liwcdict <- dictionary(file = "http://www.kenbenoit.net/files/LIWC2001_English.dic",
                       format = "LIWC")
dfm(inaugTexts, dictionary=liwcdict)