Why have regular expressions survived seven decades of technological disruption? Because coders who understand regular expressions have a massive advantage when working with textual data. They can write in a single line of code what takes others dozens!<\/p>\n
This article is all about the re.split(pattern, string)<\/strong> method of Python’s\u00a0re library<\/a>.<\/p>\n Let’s answer the following question:<\/p>\n The re.split(pattern, string, maxsplit=0, flags=0)<\/strong> method returns a list of strings by matching all occurrences of the pattern in the string and dividing the string along those.<\/strong><\/p>\n Here’s a minimal example:<\/p>\n The string contains four words that are separated by whitespace characters (in particular: the empty space ‘ ‘ and the tabular character ‘\\t’). You use the regular expression ‘\\s+’ to match all occurrences of a positive number of subsequent whitespaces. The matched substrings serve as delimiters. The result is the string divided along those delimiters.<\/p>\n But that’s not all! Let’s have a look at the formal definition of the split method.<\/p>\n Specification<\/strong><\/p>\n The method has four arguments—two of which are optional.<\/p>\n The first and second arguments are required. The third and fourth arguments are optional. <\/p>\n You’ll learn about those arguments in more detail later. <\/p>\n Return Value:<\/strong><\/p>\n The regex split method returns a list of substrings obtained by using the regex as a delimiter.<\/p>\n Let’s study some more examples—from simple to more complex.<\/p>\n The easiest use is with only two arguments: the delimiter regex and the string to be split.<\/p>\n You use an arbitrary number of ‘f’ or ‘g’ characters as regular expression delimiters. How do you accomplish this? By combining the character class regex What if you don’t want to split the whole string but only a limited number of times. Here’s an example:<\/p>\n We use the simple delimiter regex ‘-‘ to divide the string into substrings. In the first method call, we set maxsplit=5 to obtain six list elements. In the second method call, we set maxsplit=3 to obtain three list elements. Can you see the pattern?<\/p>\n You can also use positional arguments to save some characters:<\/p>\n But as many coders don’t know about the maxsplit argument, you probably should use the keyword argument for readability.<\/p>\n As you’ve seen in the specification, the re.split() method comes with an optional fourth ‘flag’ argument:<\/p>\n What’s the purpose of the flags argument<\/a>?<\/p>\n Flags allow you to control the regular expression engine. Because regular expressions are so powerful, they are a useful way of switching on and off certain features (for example, whether to ignore capitalization when matching your regex). <\/p>\nHow Does re.split() Work in Python?<\/h2>\n
>>> import re\n>>> string = 'Learn Python with\\t Finxter!'\n>>> re.split('\\s+', string)\n['Learn', 'Python', 'with', 'Finxter!']<\/pre>\nre.split(pattern, string, maxsplit=0, flags=0)<\/pre>\n
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Regex Split Minimal Example<\/h2>\n
>>> import re\n>>> string = 'fgffffgfgPythonfgisfffawesomefgffg'\n>>> re.split('[fg]+', string)\n['', 'Python', 'is', 'awesome', '']<\/pre>\n[A]<\/code> and the one-or-more regex A+<\/code> into the following regex: [fg]+<\/code>. The strings in between are added to the return list.<\/p>\nHow to Use the maxsplit Argument?<\/h2>\n
>>> string = 'a-bird-in-the-hand-is-worth-two-in-the-bush'\n>>> re.split('-', string, maxsplit=5)\n['a', 'bird', 'in', 'the', 'hand', 'is-worth-two-in-the-bush']\n>>> re.split('-', string, maxsplit=2)\n['a', 'bird', 'in-the-hand-is-worth-two-in-the-bush']<\/pre>\n >>> re.split('-', string, 2)\n['a', 'bird', 'in-the-hand-is-worth-two-in-the-bush']<\/pre>\nHow to Use the Optional Flag Argument?<\/h2>\n
re.split(pattern, string, maxsplit=0, flags=0)<\/pre>\n