tm_map和stopwords无法从R中创建的语料库中删除不需要的单词

Question

I have a resulting data frame which has the following data:

                   word freq
credit           credit  790
account         account  451
xxxxxxxx       xxxxxxxx  430
report           report  405
information information  368
reporting     reporting  345
consumer       consumer  331
accounts       accounts  300
debt               debt  170
company         company  152
xxxxxx         xxxxxx    147

I want to do the following:

• remove all the wods which has more than two x such as xx, xxx, xxx and so forth, since these words can be in lower or upper case so have to bring into lower case first then remove

I am using tm_map for removing the stopwords but it seems, it didn't work and I still got the unwanted words in the dataframe as above.

myCorpus <- Corpus(VectorSource(df$txt))
myStopwords <- c(stopwords('english'),"xxx", "xxxx", "xxxxx", 
                 "XXX", "XXXX", "XXXXX", "xxxx", "xxx", "xx", "xxxxxxxx",
                 "xxxxxxxx", "XXXXXX", "xxxxxx", "XXXXXXX", "xxxxxxx", "XXXXXXXX", "xxxxxxxx")
myCorpus <- tm_map(myCorpus, tolower)
myCorpus<- tm_map(myCorpus,removePunctuation)
myCorpus <- tm_map(myCorpus, removeNumbers)
myCorpus <- tm_map(myCorpus, removeWords, myStopwords)

myTdm <- as.matrix(TermDocumentMatrix(myCorpus))
v <- sort(rowSums(myTdm), decreasing=TRUE)
FreqMat <- data.frame(word = names(v), freq=v, row.names = F)
head(FreqMat, 10)

This code above didn't work for me for removing unwanted words from corpus.

is there any other alternative to deal with this issue?

Answer 1

One possibility involving dplyr and stringr could be:

df %>%
 mutate(word = tolower(word)) %>%
 filter(str_count(word, fixed("x")) <= 1)

         word freq
1      credit  790
2     account  451
3      report  405
4 information  368
5   reporting  345
6    consumer  331
7    accounts  300
8        debt  170
9     company  152

Or a base R possibility using a similar logic:

df[sapply(df[, 1], 
          function(x) length(grepRaw("x", tolower(x), all = TRUE, fixed = TRUE)) <= 1, 
          USE.NAMES = FALSE), ]