我有一个用字符串填充的列表:string<- c("SPG_L_subgenual_ACC_R", "SPG_R_MTG_L_pole", "MTG_L_pole_CerebellumGM_L")
我需要分割字符串,使它们看起来像:
"SPG_L", "subgenual_ACC_R", "SPG_R", "MTG_L_pole", "MTG_L_pole", "CerebellumGM_L"
我尝试使用以下正则表达式来分割字符串:
str_split(string,'(?<=[[RL]|pole])_')
但这导致:
"SPG_L", "subgenual" "ACC_R", "SPG_R", "MTG_L", "pole", "MTG_L", "pole", "CerebellumGM_L"
我如何编辑正则表达式,以便在第一次出现“ R”,“ L”之后在“ _”处拆分每个字符串元素,除非第一次出现“ R”或“ L”之后是“ pole” ,那么它将在第一次出现“ pole”之后拆分字符串元素,并且仅拆分每个字符串元素一次?
split_again = function(x){
if(length(x) > 1){
return(x)
}
else{
str_split(
string = x,
pattern = '(?<=[R|L])_',
n = 2)
}
}
str_split(
string = string,
pattern = '(?<=pole)_',
n = 2) %>%
lapply(split_again) %>%
unlist()