替换R中文本列中的一些字符

Question

我有一个包含文本列的数据集，其中包含文本和一个以诸如sa之类的术语开头并在following digits的术语。 字母可以是从 a 到 z 的任何字母，可以是小写字母也可以是大写字母。 数据快照如下：

df_new <- data.frame(
  given_info=c('SA12 is given','he has his sa12',
         'she will get Sr15','why not having an ra31',
         'his tA23 is missing', 'pa12 is given'))

df_new %>% select(given_info)

              given_info
1          SA12 is given
2        he has his sa12
3      she will get Sr15
4 why not having an ra31
5    his tA23 is missing
6          pa12 is given

我需要用术语document替换任何具有sa (or any other combinations of two random letters with the two digits 。因此，感兴趣的结果是：

              given_info
1          document is given
2        he has his document
3      she will get document
4      why not having an document
5    his document is missing
6          document is given

非常感谢您的提前帮助！

Answer 1

我们可以在这里使用gsub()如下：

df_new$given_info <- gsub("\\b[A-Za-z]{2}\\d{2}\\b", "document", df_new$given_info)
df_new

                  given_info
1          document is given
2        he has his document
3      she will get document
4 why not having an document
5    his document is missing
6          document is given

此处使用的正则表达式模式表示匹配：

• \b单词边界（意味着前面的不是单词字符）
• [A-Za-z]{2}匹配任意 2 个字母
• \d{2}匹配 2 个数字
• \b另一个单词边界（数字后面的不是单词字符）

例如，单词边界确保文本中的abc12不会被替换为document 。 如果我们不使用 boundaries 这个词，那么你也会得到 substring 个匹配项，这可能是你不想要的。