{"id":108031,"date":"2020-01-25T12:37:14","date_gmt":"2020-01-25T12:37:14","guid":{"rendered":"https:\/\/blog.finxter.com\/?p=5861"},"modified":"2020-01-25T12:37:14","modified_gmt":"2020-01-25T12:37:14","slug":"python-regex-sub","status":"publish","type":"post","link":"https:\/\/sickgaming.net\/blog\/2020\/01\/25\/python-regex-sub\/","title":{"rendered":"Python Regex Sub"},"content":{"rendered":"

Do you want to replace all occurrences of a pattern in a string? You’re in the right place! This article is all about the re.sub(pattern, string)<\/strong> method of Python’s re library<\/a>. <\/p>\n

Let’s answer the following question:<\/p>\n

How Does re.sub() Work in Python?<\/h2>\n

The re.sub(pattern, repl, string, count=0, flags=0)<\/strong> method returns a new string where all occurrences of the pattern in the old string are replaced by repl.<\/strong><\/p>\n

Here’s a minimal example:<\/p>\n

>>> import re\n>>> text = 'C++ is the best language. C++ rocks!'\n>>> re.sub('C\\+\\+', 'Python', text) 'Python is the best language. Python rocks!'\n>>> <\/pre>\n
The text contains two occurrences of the string ‘C++’. You use the re.sub() method to search all of those occurrences. Your goal is to replace all those with the new string ‘Python’ (Python is the best language after all).<\/p>\n
Note that you must escape the ‘+’ symbol in ‘C++’ as otherwise it would mean the at-least-one<\/em> regex<\/em>. <\/p>\n
You can also see that the sub() method replaces all matched patterns in the string—not only the first one.<\/p>\n
But there’s more! Let’s have a look at the formal definition of the sub() method.<\/p>\n
Specification<\/strong><\/p>\n
re.sub(pattern, repl, string, count=0, flags=0)<\/pre>\n
The method has four arguments—two of which are optional.<\/p>\n