使用正则表达式组合在Strsplit中保留分隔符

Question

我正在修改一些需要我使用strsplit组合regex函数的strsplit 。 我已经想出了如何分割我的字符串，但我正在努力应用这篇文章中关于保持分隔符的指导。

这是我正在抓取的字符串示例：

text<-c("This activity center is fun and helps give your birds exercise! With climbing ladders, a swing, tightrope and an assortment of engaging toys, the Activity Center has everything your bird needs to relieve stress and boredom all in one place. Relieves stress & boredom Durable & brightly colored wood Easy to clean bottom Simple installation & assemblyMaterial: WoodDimensions (Overall): 12.0 inches (H) x 15.0 inches (W) x 18.5 inches (L)Weight: 6.0 poundsHolds up to: 20.0 poundsIntended Pet Type: BirdCare and Cleaning: Hand washPet activity: ClimbTCIN: 16707835UPC: 030172025594Item Number (DPCI): 083-01-0246Report incorrect product information")

并且，这里是成功拆分字符串的代码，但修剪了分隔符：

strsplit(as.character(free_text), "[0-9](?=[AZ])|[az](?=[AZ])|[')'](?=[AZ])", perl=TRUE)

正如您将注意到的，我正在寻找以下地方：

• 小写字母直接与大写字母相邻
• 大写字母旁边的数字
• 大写字母旁边的括号括号

不幸的是，下面的输出显示了我的代码的问题：

[1] "This activity center is fun and helps give your birds exercise! With climbing ladders, a swing, tightrope and an assortment of engaging toys, the Activity Center has everything your bird needs to relieve stress and boredom all in one place. Relieves stress & boredom Durable & brightly colored wood Easy to clean bottom Simple installation & assembl" [2] "Material: Woo"
[3] "Dimensions (Overall): 12.0 inches (H) x 15.0 inches (W) x 18.5 inches (L"
[4] "Weight: 6.0 pound"
[5] "Holds up to: 20.0 pound"
[6] "Intended Pet Type: Bir"
[7] "Care and Cleaning: Hand was"
[8] "Pet activity: Clim"
[9] "TCIN: 1670783"
[10] "UPC: 03017202559"
[11] "Item Number (DPCI): 083-01-024"
[12] "Report incorrect product information"

即，最后一个字母是从assemble [1] ， Wood [2]修剪的。 当你在寻找像我这样的正则表达式组合时，如何保留分隔符？

Answer 1

您可以将正则表达式中的消费模式放入lookbehinds：

> text<-c("This activity center is fun and helps give your birds exercise! With climbing ladders, a swing, tightrope and an assortment of engaging toys, the Activity Center has everything your bird needs to relieve stress and boredom all in one place. Relieves stress & boredom Durable & brightly colored wood Easy to clean bottom Simple installation & assemblyMaterial: WoodDimensions (Overall): 12.0 inches (H) x 15.0 inches (W) x 18.5 inches (L)Weight: 6.0 poundsHolds up to: 20.0 poundsIntended Pet Type: BirdCare and Cleaning: Hand washPet activity: ClimbTCIN: 16707835UPC: 030172025594Item Number (DPCI): 083-01-0246Report incorrect product information")
> strsplit(text, "(?<=[0-9])(?=[A-Z])|(?<=[a-z])(?=[A-Z])|(?<=\\))(?=[A-Z])", perl=TRUE)
[[1]]
 [1] "This activity center is fun and helps give your birds exercise! With climbing ladders, a swing, tightrope and an assortment of engaging toys, the Activity Center has everything your bird needs to relieve stress and boredom all in one place. Relieves stress & boredom Durable & brightly colored wood Easy to clean bottom Simple installation & assembly"
 [2] "Material: Wood"                                                                                                                                                                                                                                                                                                                                                
 [3] "Dimensions (Overall): 12.0 inches (H) x 15.0 inches (W) x 18.5 inches (L)"                                                                                                                                                                                                                                                                                     
 [4] "Weight: 6.0 pounds"                                                                                                                                                                                                                                                                                                                                            
 [5] "Holds up to: 20.0 pounds"                                                                                                                                                                                                                                                                                                                                      
 [6] "Intended Pet Type: Bird"                                                                                                                                                                                                                                                                                                                                       
 [7] "Care and Cleaning: Hand wash"                                                                                                                                                                                                                                                                                                                                  
 [8] "Pet activity: Climb"                                                                                                                                                                                                                                                                                                                                           
 [9] "TCIN: 16707835"                                                                                                                                                                                                                                                                                                                                                
[10] "UPC: 030172025594"                                                                                                                                                                                                                                                                                                                                             
[11] "Item Number (DPCI): 083-01-0246"                                                                                                                                                                                                                                                                                                                               
[12] "Report incorrect product information"     

查看正则表达式演示和在线R演示 。

[0-9]转换为(?<=[0-9]) ， [az]现在是(?<=[az]) ， [')']现在是(?<=\\)) 。

请注意， (?<=...)是一个正向的lookbehind ，它匹配一个字符串中的位置，该位置紧跟在lookbehind中定义的某个模式之前。