如何在R中将数据帧转换为术语文档矩阵？

# 安装和加载tm包
install.packages("tm")
library(tm)

# 创建一个数据帧
df <- data.frame(
  id = c(1, 2, 3),
  text = c("This is the first document.",
           "This document is the second document.",
           "And this is the third one.")
)

# 创建一个语料库
corpus <- Corpus(VectorSource(df$text))

# 对语料库进行预处理
corpus <- tm_map(corpus, content_transformer(tolower))
corpus <- tm_map(corpus, removePunctuation)
corpus <- tm_map(corpus, removeNumbers)
corpus <- tm_map(corpus, removeWords, stopwords("english"))
corpus <- tm_map(corpus, stripWhitespace)

# 创建术语文档矩阵
tdm <- DocumentTermMatrix(corpus)

# 查看术语文档矩阵
inspect(tdm)