A regular expression is a sequence of symbols that identifies a set of strings. They are made with special characters and sequences. In Python, a regular expression can be used through the re module.
In this shot, we will learn how to make a simple regex.
.: matches any text except a newline.
^: matches the start of the string.
＄: matches end of the string (before a newline).
*: matches zero or more patterns of a certain regex.
+: matches one or more patterns of a certain regex.
?: matches zero or one repetition of the previous regex.
{x}: matches exactly x copies of the previous regex. It can be extended specifying n repetitions with {x, y} and with ?.
\: escapes special characters.
[]: matches a set of characters.
|: work as OR between two regexes.
(): matches whatever regex is inside it and can be extended with ?.
A special sequence is identified by a \. For example, we can use:
\A: matches the start of the string.
\b: matches an empty string only if it’s not at the beginning of the string.
\S: matches any character which is not an empty string.
The re module also provides different methods to interact with strings, such as:
find()search()match()split()escape()More information about regex can be found in the official documentation here.
import rex = re.search("lo", "Hello educative!")print(x)# split at every spacex = re.split("\s", "Hello educative! 2345aa 204 hellow")print(x)