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  1. example <- c("positive_1", "positive_2", "test_20_curve", "test_60_point", "percent_total")
  2. library(stringr)
  3. str_extract(example, "(?<!\\d)\\d{2}(?!\\d)")
  4.  
Success #stdin #stdout 0.31s 42048KB
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Standard input is empty
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[1] NA   NA   "20" "60" NA
https://ideone.com/syG1hG
language:
R (R 3.5.2)
created:
2 years ago
visibility:
secret

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