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  1. a = "#'YOUR_ANSWER
  2.        As_samp2 = 36
  3.        As_samp3 = 38
  4.  
  5.        #'END_ANSWER"
  6.  
  7.  
  8. b <-gsub(pattern = "^(#'YOUR_ANSWER.*)(?:\\R(?!\\h*#'END_ANSWER$).*)*(\\R\\h*#'END_ANSWER)$", a, replace="\\1\nspace for answer\\2", per=T)
  9. print(b)
Success #stdin #stdout 0.2s 39764KB
comments (?)
stdin 
Standard input is empty
stdout 
[1] "#'YOUR_ANSWER\nspace for answer\n       #'END_ANSWER"
https://ideone.com/1AK9zV
language:
R (R 3.5.2)
created:
6 years ago
visibility:
public

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