R 中的数据框/向量上下文

Question

Not sure how to explain what I'm asking for, but here is an example of code:

aat<-as.character(lapply(
    list.files(), 
    function(i) { 
        if(regexpr('new\\_mailed',i,ignore.case=T)>0) { 
            return(i); 
        } 
    }
))

basically, this will return NULL if the filename in the current iteration doesn't satisfy the regex.

what I want to do is do as.character(..all that code here..)[only get items where not equal to NULL] without having to assign to a variable and then do variable[variable != NULL]

is this possible?

Answer 1

解决方案是使用list.files(pattern = "new\\\\_mailed")