Summary: The different methods to split a string using regex are:

• re.split()
• re.sub()
• re.findall()
• re.compile()

Minimal Example

import re text = "Earth:Moon::Mars:Phobos" # Method 1

res = re.split("[:]+", text)

print(res) # Method 2

res = re.sub(r':', " ", text).split()

print(res) # Method 3

res = re.findall("[^:\s]+", text)

print(res) # Method 4

pattern = re.compile("[^:\s]+").findall

print(pattern(text)) # Output

['Earth', 'Moon', 'Mars', 'Phobos']

Problem Formulation

Problem: Given a string and a delimiter. How will you split the string using the given delimiter using different functions from the regular expressions library?

Example: In the following example, the given string has to be split using a hyphen as the delimiter.

# Input

text = "abc-lmn-xyz" # Expected Output

['abc', 'lmn', 'xyz']

Method 1: re.split

The re.split(pattern, string) method matches all occurrences of the pattern in the string and divides the string along the matches resulting in a list of strings between the matches. For example, re.split('a', 'bbabbbab') results in the list of strings ['bb', 'bbb', 'b'].

Approach: Use the re.split function and pass [_]+ as the pattern which splits the given string on occurrence of an underscore.

Code:

import re text = "abc_lmn_xyz"

res = re.split("[_]+", text)

print(res) # ['abc', 'lmn', 'xyz']

Related Read: Python Regex Split

Method 2: re.sub

The regex function re.sub(P, R, S) replaces all occurrences of the pattern P with the replacement R in string S. It returns a new string. For example, if you call re.sub('a', 'b', 'aabb'), the result will be the new string 'bbbb' with all characters 'a' replaced by 'b'.

Approach: The idea here is to use the re.sub function to replace all occurrences of underscores with a space and then use the split function to split the string at spaces.

Code:

import re text = "abc_lmn_xyz"

res = re.sub(r'_', " ", text).split()

print(res) # ['abc', 'lmn', 'xyz']

Related Read: Python Regex Sub

Method 3: re.findall

The re.findall(pattern, string) method scans string from left to right, searching for all non-overlapping matches of the pattern. It returns a list of strings in the matching order when scanning the string from left to right.

Approach: Find all occurrences of characters that are separated by underscores using the re.findall().

Code:

import re text = "abc_lmn_xyz"

res = re.findall("[^_\s]+", text)

print(res) # ['abc', 'lmn', 'xyz']

Related Read: Python re.findall()

Method 4: re.compile

The method re.compile(pattern) returns a regular expression object from the pattern that provides basic regex methods such as pattern.search(string), pattern.match(string), and pattern.findall(string). The explicit two-step approach of (1) compiling and (2) searching the pattern is more efficient than calling, say, search(pattern, string) at once, if you match the same pattern multiple times because it avoids redundant compilations of the same pattern.

Code:

import re text = "abc_lmn_xyz"

pattern = re.compile("[^-\s]+").findall

print(pattern(text)) # ['abc', 'lmn', 'xyz']

Why use re.compile?

• Efficiency: Using re.compile() to assemble regular expressions is effective when the expression has to be used more than once. Thus, by using the classes/objects created by compile function, we can search for instances that we need within different strings without having to rewirte the expressions again and again. This increases productivity as well as saves time.
• Readability: Another advantage of using re.compile is the readability factor as it leverages you the power to decouple the specification of the regex.

Read: Is It Worth Using Python’s re.compile()?

Exercise

Problem: Python regex split by spaces, commas, and periods, but not in cases like 1,000 or 1.50.

Given:
my_string = "one two 3.4 5,6 seven.eight nine,ten"
Expected Output:
["one", "two", "3.4", "25.6" , "seven", "eight", "nine", "ten"]

Solution

my_string = "one two 3.4 25.6 seven.eight nine,ten"

res = re.split('\s|(?<!\d)[,.](?!\d)', my_string)

print(res) # ['one', 'two', '3.4', '25.6', 'seven', 'eight', 'nine', 'ten']

Conclusion

Therefore, we have learned four different ways of splitting a string using the regular expressions package in Python. Feel free to use the suitable technique that fits your needs. The idea of this tutorial was to get you acquainted with the numerous ways of using regex to split a string and I hope it helped you.

Please stay tuned and subscribe for more interesting discussions and tutorials in the future. Happy coding!

Do you want to master the regex superpower? Check out my new book The Smartest Way to Learn Regular Expressions in Python with the innovative 3-step approach for active learning: (1) study a book chapter, (2) solve a code puzzle, and (3) watch an educational chapter video.

Summary: Use given_string.splitlines() to split a given multiline string into multiple lines.

Minimal Example:

text = 'Python\nJava\nC#'

print(text.splitlines())

# Output: ['Python', 'Java', 'C#']

Problem Formulation

Problem: Given a string, How will you split the string into a list of words using newline as a separator/delimiter?

Example:

# Input

text = """abc

def

ghi """

# Expected Output

['abc', 'def', 'ghi']

Let’s dive into the different ways of solving the given problem.

Method 1: Using splitlines

Approach: The most convenient and easiest way to split a given multiline string into multiple strings is to use the splitlines() method, i.e., simply use – 'given_string'.splitlines().

NOTE: splitlines() is a built-in method in Python that splits a string at line breaks such as '\n' and returns a split list of substrings (i.e., lines). For example, 'finxter\nis\ncool'.splitlines() will return the following list: ['finxter', 'is', 'cool'].

Code:

# Input

text = """Python is an Object Oriented programming language.

COBOL is an Object Oriented programming language.

F# is an Object Oriented programming language.""" print(text.splitlines()) # Output: ['Python is an Object Oriented programming language.', 'COBOL is an Object Oriented programming language.', 'F# is an Object Oriented programming language.']

Related Read: Python String splitlines()

Method 2: Using split()

Approach: Use 'given_string'.split('\n') to split the given multiline string at line breaks.

Code:

# Input

text = """Python is an Object Oriented programming language.

COBOL is an Object Oriented programming language.

F# is an Object Oriented programming language.""" print(text.split('\n')) # Output: ['Python is an Object Oriented programming language.', 'COBOL is an Object Oriented programming language.', 'F# is an Object Oriented programming language.']

Using “\n” ensures that whenever a new line occurs, the string is split.

Related Read: Python String split()

Method 3: Using re.split in a List Comprehension

Another way to solve the given problem is to use the split method of the regex module. You can split the string at every line break by passing “\n” as the pattern within the re.split function. To ensure that there are no leading or trailing extra whitespaces in the resultant list you can use a list comprehension that stores the split strings only and eliminates whitespace characters. This can be done with the help of an if statement within the list comprehension as shown in the solution below.

Code:

import re text = """Python is an Object Oriented programming language.

COBOL is an Object Oriented programming language.

F# is an Object Oriented programming language.""" print([x for x in re.split("\n", text) if x!='']) # Output: ['Python is an Object Oriented programming language.', 'COBOL is an Object Oriented programming language.', 'F# is an Object Oriented programming language.']

NOTE: The re.split(pattern, string) method matches all occurrences of the pattern in the string and divides the string along the matches resulting in a list of strings between the matches. For example, re.split('a', 'bbabbbab') results in the list of strings ['bb', 'bbb', 'b'].

Read more here – Python Regex Split

List Comprehension: “A list comprehension consists of brackets containing an expression followed by a for clause, then zero or more for or if clauses. The result will be a new list resulting from evaluating the expression in the context of the for and if clauses which follow it.”

Read more here: List Comprehension in Python — A Helpful Illustrated Guide

Do you want to master the regex superpower? Check out my new book The Smartest Way to Learn Regular Expressions in Python with the innovative 3-step approach for active learning: (1) study a book chapter, (2) solve a code puzzle, and (3) watch an educational chapter video.

Conclusion

We have successfully solved the given problem using three different approaches. I hope you this article answered all your queries. Please subscribe and stay tuned for more interesting articles!

Happy coding!

Related Reads:
⦿ Python | Split String by Newline
⦿ Python | Split String by Whitespace
⦿ Python | Split String into Characters

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