require(quanteda)
options(width = 110)
toks_inaug <- tokens(data_corpus_inaugural)
dfmat_inaug <- dfm(toks_inaug)
print(dfmat_inaug)
## Document-feature matrix of: 59 documents, 9,439 features (91.84% sparse) and 4 docvars.
## features
## docs fellow-citizens of the senate and house representatives : among vicissitudes
## 1789-Washington 1 71 116 1 48 2 2 1 1 1
## 1793-Washington 0 11 13 0 2 0 0 1 0 0
## 1797-Adams 3 140 163 1 130 0 2 0 4 0
## 1801-Jefferson 2 104 130 0 81 0 0 1 1 0
## 1805-Jefferson 0 101 143 0 93 0 0 0 7 0
## 1809-Madison 1 69 104 0 43 0 0 0 0 0
## [ reached max_ndoc ... 53 more documents, reached max_nfeat ... 9,429 more features ]
head(colSums(dfmat_inaug), 10)
## fellow-citizens of the senate and house
## 39 7180 10183 15 5406 11
## representatives : among vicissitudes
## 19 144 108 5
dfm_group() merges documents based on a vector given to the groups argument. In grouping documents, it takes the sums of feature frequencies.
dfmat_party <- dfm_group(dfmat_inaug, groups = Party)
print(dfmat_party)
## Document-feature matrix of: 6 documents, 9,439 features (66.93% sparse) and 1 docvar.
## features
## docs fellow-citizens of the senate and house representatives : among vicissitudes
## Democratic 3 1994 2742 2 1728 4 3 54 25 3
## Democratic-Republican 10 945 1416 0 640 0 2 1 16 1
## Federalist 3 140 163 1 130 0 2 0 4 0
## none 1 82 129 1 50 2 2 2 1 1
## Republican 9 3055 4408 5 2386 4 6 86 52 0
## Whig 13 964 1325 6 472 1 4 1 10 0
## [ reached max_nfeat ... 9,429 more features ]
head(colSums(dfmat_party), 10)
## fellow-citizens of the senate and house
## 39 7180 10183 15 5406 11
## representatives : among vicissitudes
## 19 144 108 5
From quanteda package version 3.0 onwards, dfm_group() supports non-standard evaluation. This means that the name of the grouping variable should not be quoted by ".
dfm_group() identifies document-level variables that are the same within groups and keeps these variables.
docvars(dfmat_party)
## Party
## 1 Democratic
## 2 Democratic-Republican
## 3 Federalist
## 4 none
## 5 Republican
## 6 Whig