R错误:inherits(x,c("DocumentTermMatrix","TermDocumentMatrix"))不是TRUE

Question

我正在使用以下代码创建文档术语矩阵.我创建矩阵没有问题,但当我尝试删除稀疏术语或查找常用术语时,我收到错误.

text<- c("Since I love to travel, this is what I rely on every time.", 
         "I got this card for the no international transaction fee", 
         "I got this card mainly for the flight perks",
         "Very good card, easy application process",
         "The customer service is outstanding!") 

library(tm)
corpus<- Corpus(VectorSource(text))
corpus<- tm_map(corpus, content_transformer(tolower))
corpus<- tm_map(corpus, removePunctuation)
corpus<- tm_map(corpus, removeWords, stopwords("english"))
corpus<- tm_map(corpus, stripWhitespace)

dtm<- as.matrix(DocumentTermMatrix(corpus))

结果如下:

Docs    application card    customer    easy    every ... etc.
1       0           0       0           1       0
2       0           1       0           0       1
3       0           1       0           0       0
4       1           1       0           0       0
5       0           0       1           0       0

这是我使用removeSparseTerms或findFreqTerms获取错误的地方

sparse<- removeSparseTerms(dtm, 0.80)
freq<- findFreqTerms(dtm, 2)

结果

Error: inherits(x, c("DocumentTermMatrix", "TermDocumentMatrix")) is not TRUE

Answer 1

removeSparseTerms和findFreqTerms期待一个DocumentTermMatrix或TermDocumentMatrix对象不是矩阵.

创建DocumentTermMatrix而不转换为矩阵,您将不会收到错误.

dtm <- DocumentTermMatrix(corpus)
sparse <- removeSparseTerms(dtm, 0.80)
freq <- findFreqTerms(dtm, 2)