我有一个类似的代码（我知道了here）：
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
我尝试了其他方法，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。我哪里错了？
【问题讨论】：
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的术语：
如果你想得到这个的否定，你把它放在 between() 和你 //1
gsub("([\\b[a-zA-Z0-9]{4,10}\\b])", "//1", m)
“你好！#London 是 gr8。我真的很喜欢这里发生的事情！珠穆朗玛峰的 alcomb 很棒！前面提到的地方太棒了！#Wow”
有趣的是，在 2 个正则表达式中存在 4 个字母的单词。
【讨论】：
# starting string
m <- c("Hello! #London is gr8. I really likewhatishappening here! The alcomb of Mount Everest is excellent! the aforementioned place is amazing! #Wow")
# remove punctuation (optional)
v <- gsub("[[:punct:]]", " ", m)
# split into distinct words
w <- strsplit( v , " " )
# calculate the length of each word
x <- nchar( w[[1]] )
# keep only words with length 4, 5, 6, 7, 8, 9, or 10
y <- w[[1]][ x %in% 4:10 ]
# string 'em back together
z <- paste( unlist( y ), collapse = " " )
# voila
z
【讨论】：
gsub(" [^ ]{1,3} | [^ ]{11,} "," ",m)
[1] "Hello! #London gr8. really here! alcomb Mount Everest excellent! aforementioned
place amazing! #Wow"
【讨论】：
这可能会让你开始：
m <- c("Hello! #London is gr8. I really likewhatishappening here! The alcomb of Mount Everest is excellent! the aforementioned place is amazing! #Wow")
y <- gsub("\\b[a-zA-Z0-9]{1,3}\\b", "", m) # replace words shorter than 4
y <- gsub("\\b[a-zA-Z0-9]{10,}\\b", "", y) # replace words longer than 10
y <- gsub("\\s+\\.\\s+ ", ". ", y) # replace stray dots, eg "Foo . Bar" -> "Foo. Bar"
y <- gsub("\\s+", " ", y) # replace multiple spaces with one space
y <- gsub("#\\b+", "", y) # remove leftover hash characters from hashtags
y <- gsub("^\\s+|\\s+$", "", y) # remove leading and trailing whitespaces
y
# [1] "Hello! London. really here! alcomb Mount Everest excellent! place amazing!"
【讨论】：
来自 Alaxender & agstudy 的回答：
x<- gsub("\\b[a-zA-Z0-9]{1,3}\\b|\\b[a-zA-Z0-9]{10,}\\b", "", m)
现在工作！
非常感谢，伙计们！
【讨论】：
我不熟悉 R，也不知道它在正则表达式模式中支持哪些类或其他特性。没有它们，模式将是这样的
[^A-z0-9]([A-z0-9]{1,3}|[A-z0-9]{11,})[^A-z0-9]
【讨论】：
a-Z 是一个无效的字符范围，因为a 在 ASCII 表中位于 Z 之后。您可以更改顺序，但正确的是 a-zA-Z 或使用 [:alpha:] 匹配所有 ASCII 字符。