strsplit 분리자 정규식에서 escape backslash가 두개인 이유...펌

>str= "AAC|Australia Acquisition Corp. - Ordinary Shares|S|N|D|100" > strsplit(str,"\\|") [[1]] [1] "AAC" [2] "Australia Acquisition Corp. - Ordinary Shares" [3] "S" [4] "N" [5] "D" [6] "100" I wonder \\| is equal to | ? maybe \\|is equal to \| , why can strsplit(str,"\\|") work? r share|improve this question edited Aug 4 '12 at 7:52 aioobe 126k15221362 asked Aug 4 '12 at 7:25 Fnzh Xx 815
=== Since | has a special meaning in reg-exps it needs to be escaped, so to match | the actual regular ｅxpression is \| Since \ in turn is a special character when declaring string literals (you probably recognize it from \n etc.), the \ needs to be escaped itself. I.e., in order to create a string literal containing \| you need \\| ===	\\|

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Because it's a quoted string. In a quoted string, you can include a " character by escaping it with a \. A \ itself then also needs to be escaped to be a single literal backslash. So your quoted string means: \|. Now in a regular ｅxpression a | is a special character that is not matched literally unless it is escaped. Regular ｅxpressions in R also escape with a backslash, so the string literal "\\|" means the string \| which is an ｅxpression matching exactly |. Why "\\|" works is because that means matching exactly | which appears as the separator in the string you're splitting.