R正则表达式在数据帧列中第二次出现/后删除所有内容

Question

我将数据存储在如下所示的dataframe列中：

/travel
/food and drink/restaurants
/food and drink
/sports/outdoors/climbing

/news
/family

每行都有一些“ /”，但它们始终以“ /”开头。 有些行也是空白的。 我只需要将此数据转换为仅在第一个“ /”之后但在第二个“ /”之前包含文本。 我还想将结果中每个单词的首字母大写。 所以我希望结果看起来像这样：

Travel
Food And Drink
Food And Drink
Sports

News
Family

Answer 1

x <- c('/travel',
       '/food and drink/restaurants',
       '/food and drink',
       '/sports/outdoors/climbing',
       '/news',
       '/family')

大写每个字

gsub('(?<=\\b)([a-z])', '\\U\\1', x, perl =  TRUE)

# [1] "/Travel"                     "/Food And Drink/Restaurants" "/Food And Drink"            
# [4] "/Sports/Outdoors/Climbing"   "/News"                       "/Family"   

提取第一个/..组

gsub('^/([^/]+)|.', '\\1', x)

# [1] "travel"         "food and drink" "food and drink" "sports"         "news"          
# [6] "family" 

结合两者

gsub('(?<=\\b)([a-z])', '\\U\\1', gsub('^/([^/]+)|.', '\\1', x), perl =  TRUE)

# [1] "Travel"         "Food And Drink" "Food And Drink" "Sports"         "News"          
# [6] "Family"  

如果您不关心大写的“和”，则可以使用第二个gsub和tools::toTitleCase

tools::toTitleCase(gsub('^/([^/]+)|.', '\\1', x))

# [1] "Travel"         "Food and Drink" "Food and Drink" "Sports"         "News"          
# [6] "Family" 

Answer 2

require(magrittr)

txt <- c("/travel", "/food and drink/restaurants", "/food and drink", "/sports/outdoors/climbing", "", "/news", "/family")

strsplit(txt, "/") %>% sapply( '[', 2 )  #per Frank's suggestion

##  [1] "travel"         "food and drink" "food and drink" "sports"        
##  [5] NA               "news"           "family"        

Answer 3

一种快速的方法如下：我假设要收集的部分中只有单词字符\\w和空格\\s 。

char<- c("/travel","/food and drink/restaurants","/food and drink","/sports/outdoors/climbing","","/news","/family")

match <- regexpr("[\\w\\s]+",char,perl=TRUE)
regmatches(char,match)

## regmatches(char,match)
## [1] "travel"         "food and drink" "food and drink" "sports"        
## [5] "news"           "family"   

Answer 4

您可能需要安装stringi软件包（无论如何您都应该拥有它：），但是以下方法可以解决问题

stringi::stri_trans_totitle( gsub("/([^/]+)", "\\1", data))

gsub只是在第一个/后面直到第二个/或字符串的末尾选择文本。 然后stringi::stri_trans_totitle为您进行大小写转换。

> s <-c("/food and drink/restaurants", "/beer and wine", "", "/news")
> stringi::stri_trans_totitle( gsub("/([^/]+)", "\\1", s))
[1] "Food And Drinkrestaurants" "Beer And Wine"            
[3] ""                          "News"