regex - 使用正则表达式提取R中特定长度的单词

Question

我有一个类似(我得到here)的代码:

m<- c("Hello! #London is gr8. I really likewhatishappening here! The alcomb of Mount Everest is excellent! the aforementioned place is amazing! #Wow")

x<- gsub("\\<[a-z]\\{4,10\\}\\>","",m)
x

我尝试了其他方式，例如

m<- c("Hello! #London is gr8. I really likewhatishappening here! The alcomb of Mount Everest is excellent! the aforementioned place is amazing! #Wow")

x<- gsub("[^(\\b.{4,10}\\b)]","",m)
x

我需要删除长度小于4或大于10的单词。我要去哪里错了？

Answer 1

  gsub("\\b[a-zA-Z0-9]{4,10}\\b", "", m) 
 "! # is gr8. I  likewhatishappening ! The  of   is ! the aforementioned  is ! #Wow"

让我们解释一下正则表达式术语:

\b在称为“单词边界”的位置匹配。此匹配为零长度。

[a-zA-Z0-9]:字母数字

{4,10}:{min，max}

如果您想对此取反，则将其放在()之间，并取//1

gsub("([\\b[a-zA-Z0-9]{4,10}\\b])", "//1", m) 

“你好!＃伦敦是gr8。我真的很喜欢这里发生的事情!珠穆朗玛峰的蜂窝非常棒!上述地方真是太棒了!＃哇!”

有趣的是，在2个正则表达式中存在4个字母的单词。