require(quanteda)
require(quanteda.textmodels)
options(width = 110)
laver-garry.cat is a Wordstat dictionary that contain political left-right ideology keywords (Laver and Garry 2000).
dict_lg <- dictionary(file = "../../dictionary/laver-garry.cat", encoding = "UTF-8")
dfm_lookup() translates dictionary values to keys in a DFM.
toks_irish <- tokens(data_corpus_irishbudget2010, remove_punct = TRUE)
dfmat_irish <- dfm(toks_irish)
print(dfmat_irish)
## Document-feature matrix of: 14 documents, 5,129 features (81.27% sparse) and 6 docvars.
## features
## docs when i presented the supplementary budget to this house last
## Lenihan, Brian (FF) 5 73 1 539 7 23 305 99 10 6
## Bruton, Richard (FG) 2 6 0 305 0 27 172 55 0 5
## Burton, Joan (LAB) 11 40 0 428 0 37 157 53 6 4
## Morgan, Arthur (SF) 21 26 0 501 1 26 204 85 5 4
## Cowen, Brian (FF) 4 17 0 394 0 21 209 43 4 6
## Kenny, Enda (FG) 12 25 1 304 1 23 119 47 0 4
## [ reached max_ndoc ... 8 more documents, reached max_nfeat ... 5,119 more features ]
dfmat_irish_lg <- dfm_lookup(dfmat_irish, dictionary = dict_lg, levels = 1)
print(dfmat_irish_lg)
## Document-feature matrix of: 14 documents, 9 features (19.84% sparse) and 6 docvars.
## features
## docs CULTURE ECONOMY ENVIRONMENT GROUPS INSTITUTIONS LAW_AND_ORDER RURAL URBAN VALUES
## Lenihan, Brian (FF) 9 583 21 0 93 11 9 0 19
## Bruton, Richard (FG) 35 201 5 0 95 14 0 0 14
## Burton, Joan (LAB) 33 400 6 3 84 6 2 3 6
## Morgan, Arthur (SF) 56 427 10 0 63 22 2 1 18
## Cowen, Brian (FF) 16 416 24 0 63 4 8 1 13
## Kenny, Enda (FG) 26 211 8 1 53 18 0 2 8
## [ reached max_ndoc ... 8 more documents ]
dfm_lookup() cannot detect multi-word expressions since a document-feature matrix does not store information about positions of words. We recommend using tokens_lookup() to detect or tokens_copound() to compound multi-word expressions before creating a DFM.