R: save a regex match to a new variable while removing the regex match from the existing variable using `str_extract()`

I want to save a regex match to a new variable and remove the regex match from the existing variable using one function.

So in the following example, I want to remove "Speaker. " from sentence and save it to new_variable while also removing "Speaker. " from sentence.

I tried to accomplish this with str_extract(). I am able to match the desired word, but the word is not removed from sentence. (This may not be what str_extract() was designed to do, but then what is the difference between str_extract() and str_match()??)

library(stringr)

sentence <- "Speaker. I am not sure why this does not work."

for(line in sentence) {
  new_variable <- str_extract(line, "^[[:alpha:]]+\\. ") 
}

I know I can use str_replace() to remove the regex match from sentence, but I would prefer to do this with one function if possible.

library(stringr)

sentence <- "Speaker. I am not sure why this does not work."

for(line in sentence) {
  new_variable <- str_extract(line, "^[[:alpha:]]+\\. ")
  sentence <- str_replace(sentence, test, "")
}

You can use tidyr::separate_wider_regex

library(tidyr)

df <- data.frame(sentence = "Speaker. I am not sure why this does not work.")

separate_wider_regex(df, sentence, c(new_variable = "^[[:alpha:]]+\\. ", sentence = ".*"))

# A tibble: 1 × 2
  new_variable sentence                             
  <chr>        <chr>                                
1 "Speaker. "  I am not sure why this does not work.