找不到R对象中的randomForest错误 [英] randomForest in R object not found error

问题描述

# init
libs <- c("tm", "plyr", "class", "RTextTools", "randomForest")
lapply(libs, require, character.only = TRUE)

# set options
options(stringsAsFactors = FALSE)

# set parameters
labels <- read.table('labels.txt')
path <- paste(getwd(), "/data", sep="")

# clean text
cleanCorpus <- function(corpus) {
  corpus.tmp <- tm_map(corpus, removePunctuation)
  corpus.tmp <- tm_map(corpus.tmp, removeNumbers)
  corpus.tmp <- tm_map(corpus.tmp, stripWhitespace)
  corpus.tmp <- tm_map(corpus.tmp, content_transformer(tolower))
  corpus.tmp <- tm_map(corpus.tmp, stemDocument, language = "english")
  corpus.tmp <- tm_map(corpus.tmp, removeWords, stopwords("english"))
  return(corpus.tmp)
}

# build TDM
generateTDM <- function(label, path) {
  s.dir <- sprintf("%s/%s", path, label)
  s.cor <- Corpus(DirSource(directory = s.dir), readerControl = list(language = "en"))
  s.cor.cl <- cleanCorpus(s.cor)
  s.tdm <- TermDocumentMatrix(s.cor.cl)
  s.tdm <- removeSparseTerms(s.tdm, 0.7)
  return(list(name = label, tdm = s.tdm))
}

tdm <- lapply(labels, generateTDM, path = path)

# attach name
bindLabelToTDM <- function(tdm) {
  s.mat <- t(data.matrix(tdm[["tdm"]]))
  s.df <- as.data.frame(s.mat, stringsAsFactors = FALSE)
  s.df <- cbind(s.df, rep(tdm[["name"]], nrow(s.df)), row.names = NULL)
  colnames(s.df)[ncol(s.df)] <- "targetlabel"
  return(s.df) 
}

labelTDM <- lapply(tdm, bindLabelToTDM)

# stack
tdm.stack <- do.call(rbind.fill, labelTDM)
tdm.stack[is.na(tdm.stack)] <- 0

# hold-out
train.idx <- sample(nrow(tdm.stack), ceiling(nrow(tdm.stack) * 0.7))
test.idx <- (1:nrow(tdm.stack)) [- train.idx]

tdm.lab <- tdm.stack[, "targetlabel"]
tdm.stack.nl <- tdm.stack[, !colnames(tdm.stack) %in% "targetlabel"]

train <- tdm.stack[train.idx, ]
test <- tdm.stack[test.idx, ]

train$targetlabel <- as.factor(train$targetlabel)
label.rf <- randomForest(targetlabel ~ ., data = train, ntree = 5000, mtry = 15, importance = TRUE)

我正在尝试使用randomForest算法对文本文件进行多类分类.我得到的错误可能是由于最后一行或倒数第二行.

I am trying multi class classfication for text files using randomForest algorithms. The error I get is probably because of the last or second last line.

Error in eval(expr, envir, enclos) : object '∗' not found

tdm.stack包含名称在文档中找到的单词作为名称和其频率作为其单元格值的列.最后一列包含类的值.

tdm.stack contains columns with names as words found in the document and their cell values as their frequency. The last column contains the class value.

我已经尝试了所有无法解决的问题.请帮忙.

I have tried everything I cant figure out the problem. Please help.

推荐答案

该错误是由于我的主体中存在非ASCII字符引起的. 我将此行添加到cleanCorpus函数中，以删除非ASCII字符

The error was being caused by the presence of non-ASCII characters in my corpuses. I added this line to my cleanCorpus function to remove non-ASCII characters

corpus.tmp <- tm_map(corpus.tmp, function(x) iconv(x, "latin1", "ASCII", sub=""))

这解决了问题.

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