更改字符串在R中较大字符串中的位置

Question

我有一个字符列，如下所示：

names <- c("Isle North East", "London Northwestern", "Bedfordshire North East", "Southwark and Bermondsey North East",
           "Middlesbrough South and Cleveland East")

我想做的是将表达式 "North East" 移动到它之前出现的任何单词之前。因此，如果字符串是 XXXX XXXX North East，例如我希望它是“XXXX North East XXXX”。如果我展示我正在寻找的解决方案，也许会更容易：

ideal.names <- c("North East Isle", "London Northwestern", "North East Bedfordshire", "Southward and North East Bermondsey",
             "Middlesbrough South and Cleveland East")

我尝试了不同的方法，例如：

c(sub('^(.*) North East', 'North East \\1', names))

但这会返回以下内容：

[1] "North East Isle"                        "London Northwestern"                   
[3] "North East Bedfordshire"                "North East Southwark and Bermondsey"   
[5] "Middlesbrough South and Cleveland East"

所以问题是这会将字符串North East 移动到字符串的开头，而不是在它之前的单词之前。所以我得到North East Southwark and Bermondsey 而不是Southward and North East Bermondsey，这就是我想要的。 任何帮助都会很棒。 谢谢！

Answer 1

你可以使用

gsub('(\\S+) (North East)', '\\2 \\1', names)
## => [1] "North East Isle"                        "London Northwestern"                    "North East Bedfordshire"                "Southwark and North East Bermondsey"   
##    [5] "Middlesbrough South and Cleveland East"

详情

• (\S+) - 第 1 组 (\1)：一个或多个非空格
• - 一个空格
• (North East) - 第 2 组 (\2)：North East 字符串。

请参阅regex demo。