在句子中保留某些单词

Question

我有一个包含文本的 dataframe，我试图只保留文本中存储在向量中的某些单词，并删除不在向量中的单词。 请帮助我实现这一目标！

stopwords <- c("the","weather","looks","rainy","sunny")
df <- data.frame(a = c("a1", "a2", "a3"), text = c("today the weather looks hot", "its so rainy outside", "today its sunny"))

预期 Output：

   a                        text          new_text
1 a1 Today the weather looks hot the weather looks
2 a2        its so rainy outside             rainy
3 a3             today its sunny             sunny

我试过的代码：

df$new_text <- trimws(gsub(paste0("\\b", stopwords, "\\b",
               collapse = "|"), stopwords, df$text))

代码导致错误的重复，请帮助！

Answer 1

应该有一个直接的正则表达式来执行此操作，但是我们也可以拆分单词并找到常见的单词

sapply(strsplit(df$text, "\\s+"), function(x) 
      paste0(intersect(x, stopwords), collapse = " "))

#[1] "the weather looks" "rainy"             "sunny" 

数据

df <- data.frame(a = c("a1", "a2", "a3"), text = c("today the weather looks hot", 
     "its so rainy outside", "today its sunny"), stringsAsFactors = FALSE)