R中的文本挖掘

Question

我想从具有特定句子（两个或多个单词组合）而不是单个单词的文本创建TDM。句子可以是例如"climate change"，"global worming"，"lad use"等。我看过的例子都是单词。

tabela = DocumentTermMatrix(textolimpo,
         list(dictionary = c("climate change","global worming","land use")))

如果有人能帮助我，我感激不尽。

干杯。

圣拉斐尔

Answer 1

我建议quanteda：

library(quanteda)
textolimpo <- c("This climate change concerns me. This climate changes", "Wormed: global worming increased")
(dfm <- dfm(textolimpo, 
           ngrams=2L,
           dictionary = list(climate="climate_change",
                             warm="global_worming"), 
           valuetype = "regex"))
# 2 x 2 sparse Matrix of class "dfmSparse"
#        features
# docs    climate warm
#   text1       2    0
#   text2       0    1
(dfm <- dfm(textolimpo, 
            ngrams=2L, 
            thesaurus = list(climate="climate_change",
                             warm="global_worming"), 
            valuetype = "regex"))
# 2 x 8 sparse Matrix of class "dfmSparse"
#       this_climate change_concerns concerns_me me_this wormed_global worming_increased CLIMATE WARM
# text1            2               1           1       1             0                 0       2    0
# text2            0               0           0       0             1                 1       0    1