我尝试使用tm_map. 它给出了以下错误。我怎样才能解决这个问题？
require(tm)
byword<-tm_map(byword, tolower)
Error in UseMethod("tm_map", x) :
no applicable method for 'tm_map' applied to an object of class "character"
问问题
66172 次
4 回答
102
使用基本 R 函数tolower()：
tolower(c("THE quick BROWN fox"))
# [1] "the quick brown fox"
于 2012-11-30T06:41:32.717 回答
6
在这里将我的评论扩展到更详细的答案：您必须将其包裹tolower在内部，content_transformer以免搞砸VCorpus对象-例如：
> library(tm)
> data('crude')
> crude[[1]]$content
[1] "Diamond Shamrock Corp said that\neffective today it had cut its contract prices for crude oil by\n1.50 dlrs a barrel.\n The reduction brings its posted price for West Texas\nIntermediate to 16.00 dlrs a barrel, the copany said.\n \"The price reduction today was made in the light of falling\noil product prices and a weak crude oil market,\" a company\nspokeswoman said.\n Diamond is the latest in a line of U.S. oil companies that\nhave cut its contract, or posted, prices over the last two days\nciting weak oil markets.\n Reuter"
> tm_map(crude, content_transformer(tolower))[[1]]$content
[1] "diamond shamrock corp said that\neffective today it had cut its contract prices for crude oil by\n1.50 dlrs a barrel.\n the reduction brings its posted price for west texas\nintermediate to 16.00 dlrs a barrel, the copany said.\n \"the price reduction today was made in the light of falling\noil product prices and a weak crude oil market,\" a company\nspokeswoman said.\n diamond is the latest in a line of u.s. oil companies that\nhave cut its contract, or posted, prices over the last two days\nciting weak oil markets.\n reuter"
于 2016-07-20T08:07:13.860 回答
3
myCorpus <- Corpus(VectorSource(byword))
myCorpus <- tm_map(myCorpus , tolower)
print(myCorpus[[1]])
于 2013-07-25T17:10:31.737 回答
1
以这种方式使用 tolower 有一个不良的副作用：如果您稍后尝试从语料库中创建术语文档矩阵，它将失败。这是因为最近 tm 的更改无法处理 tolower 的返回类型。相反，使用：
myCorpus <- tm_map(myCorpus, PlainTextDocument)
于 2015-06-25T19:48:43.703 回答