Question

我有一个很长的字符串，我想在其中更改单词顺序。我想使用正则表达式，因为我有多个元素要改变，我想同时学习。以下是我的字符串示例：

vec1 <- c("Internet-Devices Used to Access Internet Past 30 Days [Desktop Computer-Owned by Self]", 
     "Internet-Devices Used to Access Internet Past 30 Days [Tablet-Owned by Other HH Member]", 
     "Internet-Devices Used to Access Internet Past 30 Days [Laptop Computer-Made Available by Your Employer]",
     "Radio Stations-Listened to Past Week-Quebec City [FM-CFEL-102.1 (blvd 102.1)]")

vec1
[1] "Internet-Devices Used to Access Internet Past 30 Days [Desktop Computer-Owned by Self]"                 
[2] "Internet-Devices Used to Access Internet Past 30 Days [Tablet-Owned by Other HH Member]"                
[3] "Internet-Devices Used to Access Internet Past 30 Days [Laptop Computer-Made Available by Your Employer]"
[4] "Radio Stations-Listened to Past Week-Quebec City [FM-CFEL-102.1 (blvd 102.1)]"

我希望它成为：

[1] "Internet-Devices Used to Access Internet Past 30 Days -Owned by Self[Desktop Computer]"                 
[2] "Internet-Devices Used to Access Internet Past 30 Days -Owned by Other HH Member[Tablet]"                
[3] "Internet-Devices Used to Access Internet Past 30 Days -Made Available by Your Employer[Laptop Computer]"
[4] "Radio Stations-Listened to Past Week-Quebec City [FM-CFEL-102.1 (blvd 102.1)]"

所以我认为算法应该这样工作：

在“过去30天”后查找字符串的一部分，并在连字符处停止，
将此提取的字符串复制到主字符串的最后一个字符
从主字符串中的步骤1中删除提取的字符串（但不是您刚刚添加的字符串）。

对于第1步，我昨天提出了一个类似的问题（Ignore part of a string when splitting using regular expression in R）并用它来查找这个正则表达式(?<=Past 30 Days ).+(?![^-])，它适用于regex101.com但不适用于R（不会）停在连字符处：

reg1 <- regexec(pattern = "(?<=Past 30 Days ).+(?![^-])", vec1, perl=T)
ext1 <- unname(mapply(function(xx,yy) substr(xx, yy, yy+attr(yy,"match.length")), vec1, reg1))
ext1
[1] "[Desktop Computer-Owned by Self]"                  "[Tablet-Owned by Other HH Member]"                
[3] "[Laptop Computer-Made Available by Your Employer]" ""

正如你所看到的，它并不止于连字符。

第二步，我想到的是这样的事情：

vec2 <- unname(mapply(gsub, ext1, vec1, MoreArgs = list(pattern="]")))
vec2
[1] "Internet-Devices Used to Access Internet Past 30 Days [Desktop Computer-Owned by Self[Desktop Computer-Owned by Self]"                                  
[2] "Internet-Devices Used to Access Internet Past 30 Days [Tablet-Owned by Other HH Member[Tablet-Owned by Other HH Member]"                                
[3] "Internet-Devices Used to Access Internet Past 30 Days [Laptop Computer-Made Available by Your Employer[Laptop Computer-Made Available by Your Employer]"
[4] "Radio Stations-Listened to Past Week-Quebec City [FM-CFEL-102.1 (blvd 102.1)"

除了在向量的最后一个元素中删除“]”并且没有添加正确的字符串（因为问题1）之外，这几乎是我想要的。

最后，我删除了字符串的初始部分：

unname(mapply(gsub, paste0(stringr::str_sub(ext1, end=-2),"["), vec2, MoreArgs = list(replacement="[", fixed=T)))
[1] "Internet-Devices Used to Access Internet Past 30 Days [Desktop Computer-Owned by Self]"                 
[2] "Internet-Devices Used to Access Internet Past 30 Days [Tablet-Owned by Other HH Member]"                
[3] "Internet-Devices Used to Access Internet Past 30 Days [Laptop Computer-Made Available by Your Employer]"
[4] "Radio Stations-Listened to Past Week-Quebec City [FM-CFEL-102.1 (blvd 102.1)"

这种工作，但我遇到与第2步相同的2个问题。

我的整个代码看起来非常沉重和复杂。有没有更好的方法呢？

注意：

我不是在寻找一个超级强大的解决方案
我从来没有嵌套括号
我的字符串总是用括号

Answer 1

您可以使用

(Past 30 Days\s*)([^-]*)([^]]+)

并替换为\1\3\2。请参阅regex demo。

<强>详情

(Past 30 Days\s*) - 第1组（从替换模式引用\1反向引用）：
- Past 30 Days - 文字子字符串
- \s* - 0+ whitespaces
([^-]*) - 第2组：除-
([^]]+) - 第3组：]以外的一个或多个字符。

查看R demo online：

vec1 <- c("Internet-Devices Used to Access Internet Past 30 Days [Desktop Computer-Owned by Self]", 
     "Internet-Devices Used to Access Internet Past 30 Days [Tablet-Owned by Other HH Member]", 
     "Internet-Devices Used to Access Internet Past 30 Days [Laptop Computer-Made Available by Your Employer]",
     "Radio Stations-Listened to Past Week-Quebec City [FM-CFEL-102.1 (blvd 102.1)]")
gsub("(Past 30 Days\\s*)([^-]*)([^]]+)", "\\1\\3\\2", vec1)
# [1] "Internet-Devices Used to Access Internet Past 30 Days -Owned by Self[Desktop Computer]"                 
# [2] "Internet-Devices Used to Access Internet Past 30 Days -Owned by Other HH Member[Tablet]"                
# [3] "Internet-Devices Used to Access Internet Past 30 Days -Made Available by Your Employer[Laptop Computer]"
# [4] "Radio Stations-Listened to Past Week-Quebec City [FM-CFEL-102.1 (blvd 102.1)]"

使用正则表达式更改长字符串中的单词顺序

1 个答案: