It's possible to check, if a text or a string matches a regular expression. Regular Expressions are used in programming languages to filter texts or textstrings. You can find an implementation of a Finite State Machine in Python on our website. A finite state machine (FSM), which accepts language defined by a regular expression, exists for every regular expression. In theoretical computer science, they are used to define a language family with certain characteristics, the so-called regular languages. The term "regular expression", sometimes also called regex or regexp, has originated in theoretical computer science. This introduction will explain the theoretical aspects of regular expressions and will show you how to use them in Python scripts. Note: availability of this method depends on MicroPython port.The aim of this chapter of our Python tutorial is to present a detailed and descriptive introduction into regular expressions. Returns the 2-tuple (match.start(index), match.end(index)). Note: availability of these methods depends on MicroPython port. Return the index in the original string of the start or end of the Note: availability of this method depends on MicroPython port. Return a tuple containing all the substrings of the groups of the match. index is 0 for entire match,ġ and above for each capturing group. Match objects as returned by match() and search() methods, and passed May be up to max_split 1 elements if it’s specified). Using methods is (much) more efficient if the same regex is applied to Similar to the module-level functions match(), search() sub ( replace, string, count = 0, flags = 0, / ) ¶ Instances of this class are created using (Availability depends on MicroPython port.) Regex objects ¶Ĭompiled regular expression. DEBUG ¶įlag value, display debug information about compiled expression. Note: availability of this function depends on MicroPython port. If count is specified and non-zero then substitution will stop after If replace is a function then it must take a single argument (the match) Sequences of the form \ and \g can be used toĮxpand to the corresponding group (or an empty string for unmatched groups). With replace, and returning the new string. sub ( regex_str, replace, string, count = 0, flags = 0, / ) ¶Ĭompile regex_str and search for it in string, replacing all matches String for first position which matches regex (which still may beĠ if regex is anchored). search ( regex_str, string ) ¶Ĭompile regex_str and search it in a string. Match always happensįrom starting position in a string. match ( regex_str, string ) ¶Ĭompile regex_str and match against string. compile ( regex_str ) ¶Ĭompile regular expression, return regex object. split ( "line1 \r line2 \n line3 \r\n " ) # Result: # Functions ¶ re. Import re # As re doesn't support escapes itself, use of r"" strings is not # recommended. Special character escapes like \r, \n - use Python’s own escaping For example, r"\r\n" when used as the regularĮxpression is equivalent to "rn". Not recommended to use raw Python strings ( r"") for regularĮxpressions. are not handled specially, and will beĮquivalent to literal letters r, n, etc. For example, \* isĮquivalent to literal * (not treated as the * operator). Any other character following the backslash, exceptįor those listed above, is taken literally. Matches non “word characters” (ASCII only). Each group is capturing (a substring it captures can be accessed Match either the left-hand side or the right-hand side sub-patterns of Non-greedy version of , match one or more, with the preference Non-greedy version of *, match zero or more, with the preference Non-greedy version of ?, match zero or one, with the preference Match one or more of the previous sub-pattern. Match zero or more of the previous sub-pattern. Match zero or one of the previous sub-pattern. Individual characters and ranges are supported, Supported operators and special sequences are. Syntax supported is a subset of CPython re module (and actually isĪ subset of POSIX extended regular expressions). This module implements regular expression operations. For more information, refer to the original This module implements a subset of the corresponding CPython module,Īs described below.
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