寻找R语言中可检测字符串包含子串并返回布尔值的函数

Hey there! Let's figure out how to get that exact contains(string, substring) behavior you're looking for.

First off, base R actually has a built-in function that does exactly what you need—returns a boolean for substring presence: grepl(). The catch is its parameter order is a bit different from your ideal function: it takes the substring first, then the target string. For your example:

string <- "12345REFUND4567"
substring <- "REFUND"

grepl(substring, string)  # Returns TRUE

If you want to stick strictly to the contains(string, substring) call format you imagined, it's super easy to wrap grepl() into a custom function. Even better, we can add fixed = TRUE to ensure it matches the substring literally (no accidental regex pattern matching if your substring has special characters like . or *):

contains <- function(string, substring) {
  grepl(substring, string, fixed = TRUE)
}

# Now use it exactly how you wanted:
contains(string, substring)  # Returns TRUE

Wait, you mentioned you tried str_detect() and it didn't work—let me double-check that. From the stringr package, str_detect() does return a boolean, but its parameter order is reversed from grepl(): it takes the target string first, then the pattern. So for your example, this should work too:

library(stringr)
str_detect(string, substring)  # Also returns TRUE

Maybe you had the parameters swapped before? That's a common mix-up between base R and tidyverse string functions!

So to recap your options:

• Use base R's grepl() directly (remember grepl(substring, string))
• Build your own contains() function for the exact syntax you want
• Double-check parameter order if you go back to str_detect()

内容的提问来源于stack exchange，提问作者Luca Foerster