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  1. var <- c("a1","a2","a3","a4")
  2. s = "3*a1 + a1*a2 + 4*a3*a4 + a1*a3"
  3. block = paste(var, collapse="|")
  4. pat = paste0("\\b((?:", block, ")\\*)(?=\\b(?:", block, ")\\b)|\\*")
  5. gsub(pat, "\\1", s, perl=T)
Success #stdin #stdout 0.45s 79168KB
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Standard input is empty
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[1] "3a1 + a1*a2 + 4a3*a4 + a1*a3"
https://ideone.com/VlQcQx
language:
R (R 3.5.2)
created:
8 years ago
visibility:
secret

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