如何根据优先级单词列表(使用for循环和条件)查找和替换df中的值

我在数据框中有一列，每个单元格中有多个单词，用"；"分隔(第二栏).

my_dataframe <- data.frame( first_column = c("x", "y", "x", "x", "y"),
                            second_column = c("important; very important; not important",
                                              "not important; important; very important",
                                              "very important; important",
                                              "important; not important",
                                              "not important"))
> my_dataframe
  first_column                            second_column
1            x important; very important; not important
2            y not important; important; very important
3            x                very important; important
4            x                 important; not important
5            y                            not important

我想每个单元格保留一个单词:最重要的一个.

所以我按优先顺序列了一个单词列表:

reference_importance <- list("very important", "important", "not important")

我想在第二栏中看到:

 second_column
1 very important
2 very important
3 very important
4 important
5 not important

我试过了

for (i in 1:dim(my_dataframe)[1]) {
  for (j in 1:length(reference_importance)) {
    if (j %in% my_dataframe$second_column){
      my_dataframe$second_column[i] <- paste(j)
      break}
  }
}

Then I thought the problem was that it didn't consider the different words separated by ";" so 我试过了 this:

for (i in 1:dim(my_dataframe)[1]) {
  value_as_list <- strsplit(my_dataframe$second_column[i], ";")
  print(value_as_list)
  for (j in reference_importance) {
    if (j %in% value_as_list){
      my_dataframe$second_column[i] == j
      break}
  }
} 

但这些并没有改变我专栏中的任何内容...

(我做这个例子是为了简化，但实际上我有一个巨大的表格，里面有更多的单词和可能性.这就是为什么我try 使用循环来完成它，而不是手动分配可能的答案.)