If you are working in a single-byte locale and have marked UTF-8 Generally PCRE will be faster than the default regular expressionĮngine, and fixed = TRUE faster still (especially when each Very long strings, you will want to consider the options used. If you are doing a lot of regular expression matching, including on This is regarded as a non-match, usually with a warning. Where matching failed because of resource limits (especially for PCRE) Interpretation of positions and length and the attributes follows Giving the lengths of the matches (or \(-1\) for no match). Pattern, with attribute "match.length" a vector Substrings corresponding to parenthesized subexpressions of Sequence of integers with the starting positions of the match and all Regexec returns a list of the same length as text eachĮlement of which is either \(-1\) if there is no match, or a Regexpr, except that the starting positions of every (disjoint) Gregexpr returns a list of the same length as text eachĮlement of which is of the same form as the return value for Named capture is used there are further attributes UseBytes with value TRUE is set on the result). UseBytes = TRUE is used, when they are in bytes (as they areįor an ASCII-only matching: in either case an attribute The match positions and lengths are in characters unless Integer vector giving the length of the matched text (or \(-1\) for \(-1\) if there is none, with attribute "match.length", an Text giving the starting position of the first match or Regexpr returns an integer vector of the same length as Such strings can be re-encoded by enc2native. UTF-8 input, and in a multibyte locale unless fixed = TRUE). Will often be in UTF-8 with a marked encoding (e.g., if there is a If useBytes = FALSE a non-ASCII substituted result Elements of character vectors x whichĪre not substituted will be returned unchanged (including any declaredĮncoding). Length and with the same attributes as x (after possibleĬoercion to character). Sub and gsub return a character vector of the same Grepl returns a logical vector (match or not for each element of Selected elements of x (after coercion, preserving names but no Grep(value = TRUE) returns a character vector containing the Is a long vector, when it will be a double vector. This will be an integer vector unless the input Of the elements of x that yielded a match (or not, for Grep(value = FALSE) returns a vector of the indices If NA, all elements in the resultĬorresponding to matches will be set to NA. If aĬharacter vector of length 2 or more is supplied, the first element Lower case and "\E" to end case conversion. "\L" to convert the rest of the replacement to upper or Perl = TRUE only, it can also contain "\U" or "\9" to parenthesized subexpressions of pattern. Forįixed = FALSE this can include backreferences "\1" to Regexec(pattern, text, ignore.case = FALSE, perl = FALSE,įixed = FALSE, useBytes = FALSE) ArgumentsĪ replacement for matched pattern in sub and Gregexpr(pattern, text, ignore.case = FALSE, perl = FALSE, Regexpr(pattern, text, ignore.case = FALSE, perl = FALSE, Gsub(pattern, replacement, x, ignore.case = FALSE, perl = FALSE, Sub(pattern, replacement, x, ignore.case = FALSE, perl = FALSE, Grepl(pattern, x, ignore.case = FALSE, perl = FALSE, Usage grep(pattern, x, ignore.case = FALSE, perl = FALSE, value = FALSE,įixed = FALSE, useBytes = FALSE, invert = FALSE) Sub and gsub perform replacement of the first and all Regexec search for matches to argument pattern withinĮach element of a character vector: they differ in the format of and Grep: Pattern Matching and Replacement Description
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