如何仅从存储的单词列表中生成text2vector中的文档术语矩阵

您只能从特定的功能集创建文档术语矩阵:

v = create_vocabulary(c("word1", "word2"))
vectorizer = vocab_vectorizer(v)
dtm_test = create_dtm(it, vectorizer)

然而,我不建议1)在如此稀疏的数据上使用随机林-它不会很好地工作2)按照您描述的方式执行特征选择-您可能会过度拟合。

量子田 dfm_select() dfm1 以下具有与相同的功能 dfm2 :

txts <- c("a b c d", "a a b b", "b c c d e f")

(dfm1 <- dfm(txts[1:2]))
## Document-feature matrix of: 2 documents, 4 features (25% sparse).
## 2 x 4 sparse Matrix of class "dfmSparse"
##        features
## docs    a b c d
##   text1 1 1 1 1
##   text2 2 2 0 0
(dfm2 <- dfm(txts[2:3]))
## Document-feature matrix of: 2 documents, 6 features (41.7% sparse).
## 2 x 6 sparse Matrix of class "dfmSparse"
##        features
## docs    a b c d e f
##   text1 2 2 0 0 0 0
##   text2 0 1 2 1 1 1

dfm_select(dfm1, dfm2, valuetype = "fixed", verbose = TRUE)
## kept 4 features, padded 2 features
## Document-feature matrix of: 2 documents, 6 features (50% sparse).
## 2 x 6 sparse Matrix of class "dfmSparse"
##        features
## docs    a b c d e f
##   text1 1 1 1 1 0 0
##   text2 2 2 0 0 0 0