R:如何向外搜索向量中的正则表达式？

Question

在R中是否可以在向量中搜索正则表达式,就好像所有元素都是折叠的单个元素一样？如果我们将所有元素折叠成一个来做这个,那么在搜索之后就不可能将它们放回到它们的元素形式.

这是一个向量.

vector<-c("I", "met", "a", "cow")

现在,搜索词是"meta"(元素2和3折叠).

假设我的任务是合并搜索字符串所在的两个元素.

所以我期待的是:

vector = "I", "meta", "cow"

是否有可能做到这一点？请帮忙.

Answer 1

如果您想要匹配"meta"但不匹配的东西"taco"，这将解决问题：

myFun <- function(vector, word) {
    D <- "UnLiKeLyStRiNg" 

    ## Construct a string on which you'll perform regex-search
    xx <- paste0(paste0(D, vector, collapse=""), D)

    ## Construct the regex pattern
    start <- paste0("(?<=", D, ")")
    mid <- paste0(strsplit(word, "")[[1]], collapse=paste0("(", D, ")?"))
    end <- paste0("(?=", D, ")")
    pat <- paste0(start, mid, end)

    ## Use it
    strsplit(gsub(pat, word, xx, perl=TRUE), D)[[1]][-1]
}

vector <- c("I", "met", "a", "cow")

myFun(vector, "meta")
# [1] "I"    "meta" "cow" 
myFun(vector, "taco")
# [1] "I"   "met" "a"   "cow"
myFun(vector, "Imet")
# [1] "Imet" "a"    "cow" 
myFun(vector, "Ime")
# [1] "I"   "met" "a"   "cow"