Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns - Iceweasel. Regular Expression HOWTO — Python v3.2.1 documentation - Iceweasel. Introduction Regular expressions (called REs, or regexes, or regex patterns) are essentially a tiny, highly specialized programming language embedded inside Python and made available through the re module. Using this little language, you specify the rules for the set of possible strings that you want to match; this set might contain English sentences, or e-mail addresses, or TeX commands, or anything you like. You can then ask questions such as “Does this string match the pattern?” , or “Is there a match for the pattern anywhere in this string?”. You can also use REs to modify a string or to split it apart in various ways. Regular expression patterns are compiled into a series of bytecodes which are then executed by a matching engine written in C.
The regular expression language is relatively small and restricted, so not all possible string processing tasks can be done using regular expressions. Simple Patterns We’ll start by learning about the simplest possible regular expressions. \d \s \w. Python - Regular Expressions. A regular expression is a special sequence of characters that helps you match or find other strings or sets of strings, using a specialized syntax held in a pattern. Regular expressions are widely used in UNIX world. The module re provides full support for Perl-like regular expressions in Python. The re module raises the exception re.error if an error occurs while compiling or using a regular expression. We would cover two important functions, which would be used to handle regular expressions. But a small thing first: There are various characters, which would have special meaning when they are used in regular expression.
The match Function This function attempts to match RE pattern to string with optional flags. Here is the syntax for this function − re.match(pattern, string, flags=0) Here is the description of the parameters: The re.match function returns a match object on success, None on failure. Example #! When the above code is executed, it produces following result − The search Function #!
Python - Change from re.findall(regex, text) to nltk.Text.findall(regex) Python - Regular Expressions.