从向量2中删除在向量1中找到的字符串

问题描述

我有两个向量:

sample1 <- c(".aaa", ".aarp", ".abb", ".abbott", ".abogado")
sample2 <- c("try1.aarp", "www.tryagain.aaa", "255.255.255.255", "onemoretry.abb.abogado")

我正在尝试删除在sample2中找到的sample1字符串.我得到的最接近的是通过使用sapply进行迭代，这给了我:

I am trying to remove sample1 strings that are found in sample2. The closest I got is by iterating using sapply, which gave me this:

 sapply(sample1, function(i)gsub(i, "", sample2))

     .aaa                     .aarp                    .abb                 .abbott                  .abogado          
[1,] "try1.aarp"              "try1"                   "try1.aarp"          "try1.aarp"              "try1.aarp"       
[2,] "www.tryagain"           "www.tryagain.aaa"       "www.tryagain.aaa"   "www.tryagain.aaa"       "www.tryagain.aaa"
[3,] "255.255.255.255"        "255.255.255.255"        "255.255.255.255"    "255.255.255.255"        "255.255.255.255" 
[4,] "onemoretry.abb.abogado" "onemoretry.abb.abogado" "onemoretry.abogado" "onemoretry.abb.abogado" "onemoretry.abb"  

当然预期的输出应该是

[1] "www.tryagain"    "try1"            "onemoretry"      "255.255.255.255"

感谢您的时间.

推荐答案

尝试一下，

sample1 <- c(".aaa", ".aarp", ".abb", ".abbott", ".abogado")
sample2 <- c("try1.aarp", "www.tryagain.aaa", "255.255.255.255", "onemoretry.abb.abogado")
paste0("(",paste(sub("\\.", "\\\\.", sample1), collapse="|"),")\\b")
# [1] "(\\.aaa|\\.aarp|\\.abb|\\.abbott|\\.abogado)\\b"
gsub(paste0("(",paste(sub("\\.", "\\\\.", sample1), collapse="|"),")\\b"), "", sample2)
# [1] "try1"            "www.tryagain"    "255.255.255.255" "onemoretry" 

说明:

• sub("\\.", "\\\\.", sample1)转义所有点.由于点是正则表达式中的特殊字符.

• sub("\\.", "\\\\.", sample1) escapes all the dots. Since dots are special chars in regex.

paste(sub("\\.", "\\\\.", sample1), collapse="|")将所有元素与|用作分隔符.

paste(sub("\\.", "\\\\.", sample1), collapse="|") combines all the elements with | as delimiter.

paste0("(",paste(sub("\\.", "\\\\.", sample1), collapse="|"),")\\b")创建一个正则表达式，类似于捕获组内存在的所有元素，后跟单词边界. \\b是这里急需的一个.这样它就可以进行精确的单词匹配.

paste0("(",paste(sub("\\.", "\\\\.", sample1), collapse="|"),")\\b") creates a regex like all the elements present inside a capturing group followed by a word boundary. \\b is a much needed one here . So that it would do an exact word match.

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