如果字符串包含特定数字,则抓取

Question

我有一个如下的数据集 -

> a_i
 [1] "Our-Facebook-Page/td-p/3175990"                           
 [2] "Our-Facebook-Page/td-p/3175990/page/2"  
   ....    
[17] "Data-duplicate-files/td-p/4743405"                  
[18] "Data-duplicate-files/td-p/4743405/page/2"            
[19] "Subscription-Release-1-sucks/td-p/4556739"       
[20] "Subscription-Release-1-sucks/td-p/4556739/page/2"

 > b_i
[1] "Data-duplicate-files/td-p/4743405"                  
[2] "Subscription-Release-1-sucks/td-p/4556739"
[3] "Quick-fix/td-p/4556740"

我的目标是找到仅存在于b_i中的7位数字(例如4743405,4556739,4556740),并从包含相应数字的a_i中获取数据.所以最终输出将是这样的 -

[1] "Data-duplicate-files/td-p/4743405"                  
[2] "Data-duplicate-files/td-p/4743405/page/2"            
[3] "Subscription-Release-1-sucks/td-p/4556739"       
[4] "Subscription-Release-1-sucks/td-p/4556739/page/2""

我能够使用strsplit(b_i,"/")获取数字但我仍然在抓取包含匹配数字的列表.是否有任何优雅的方式来映射这些数字并获取列表？

Answer 1

a_i[grep( paste( gsub("(^.+/)([[:digit:]])(/.+$)", "\\2", b_i), 
                 collapse="|"), 
     a_i)]
[1] "Data-duplicate-files/td-p/4743405"               
[2] "Data-duplicate-files/td-p/4743405/page/2"        
[3] "Subscription-Release-1-sucks/td-p/4556739"       
[4] "Subscription-Release-1-sucks/td-p/4556739/page/2"

这构造了一串由管道符号分隔的数字字符串,形成一个greppish-OR模式.如果你想强制执行7位数规则,你可以放置一个{}重复量词.目前它会接受正斜杠之间的任意数字位数.