R 从字符串列中的向量中查找第一个匹配的单词

发布于01月18日

我需要知道向量中的哪个词在字符串中排在第一位.我需要在一个包含数百万条记录的大型数据框上运行此代码.

df是我的样本数据

df <- data.frame(ID = c(1,2,3),
Text = c("A basket of fruits having apples, green bananas, and peaches",
"A basket of fruits having green bananas, apples, and peaches",
"A basket of fruits having peaches, green bananas, and apples"))

我要匹配的单词在一个向量中

vec <- c("green bananas", "apples", "peaches")

我希望每个记录都有一个这样的结果列

df$Result 
"apples", "green bananas", "peaches"

推荐答案

你可以使用regmatches+regexpr，如下所示

transform(
    df,
    Result = regmatches(Text, regexpr(paste0(vec, collapse = "|"), Text))
)

或str_extract

df %>%
    mutate(Result = str_extract(Text, paste0(vec, collapse = "|")))

这给了我们

  ID                                                         Text        Result
1  1 A basket of fruits having apples, green bananas, and peaches        apples
2  2 A basket of fruits having green bananas, apples, and peaches green bananas
3  3 A basket of fruits having peaches, green bananas, and apples       peaches