cbind中的行数不同

Question

我试图获取每个帖子中使用的单词的频率，并将它们作为列添加到训练数据中，下面的代码适当地运行1个单词，对于第二个单词，它会抛出此错误。

获取1000个帖子中特定单词的频率的功能

word_frequency <- function(w){

  for(i in 2:1000){
    review_text <- paste(Train$Post[i:i], collapse=" ")
    review_source <- VectorSource(review_text)

    corpus <- Corpus(review_source)
    corpus <- tm_map(corpus, content_transformer(tolower))
    corpus <- tm_map(corpus, removePunctuation)
    corpus <- tm_map(corpus, stripWhitespace)
    corpus <- tm_map(corpus, removeWords, stopwords("english"))

    dtm <- DocumentTermMatrix(corpus)
    dtm2 <- as.matrix(dtm)
    frequency <- colSums(dtm2)
    frequency <- frequency[names(frequency) == w]
    frequency <- as.list(frequency)

    freq<-rbind(freq, frequency)
    freq.withNA <- sapply(freq, function(x) ifelse(x == "NULL", NA, x))
  } 
  return(freq)
}

Train <- Training[1:1000,]

将我的词汇表中的所有单词和cbind-ing频率放到基础数据框中。

for (w in wordlist) {
  freq <- as.integer()
  new <- word_frequency(w)
  Train <- cbind(Train, new)
  print(paste("Completed word ", w, sep=""))
}