Python Re Module (Regular Expressions)
The re module provides regular expression matching operations similar to those found in Perl. Regular expressions are a powerful tool for various kinds of string manipulation.
Importing the Module
import reBasic Patterns
.: Matches any character except a newline.^: Matches the start of the string.$: Matches the end of the string.*: Matches 0 or more repetitions.+: Matches 1 or more repetitions.\d: Matches any decimal digit.\w: Matches any alphanumeric character.
Searching and Matching
re.search()
Scans through the string looking for the first location where the regular expression pattern produces a match.
import re
text = "The rain in Spain"
x = re.search(r"\bS\w+", text)
print(x.group()) # Output: Spainre.match()
Checks for a match only at the beginning of the string.
x = re.match(r"The", text) # Matches
y = re.match(r"rain", text) # None (not at start)re.findall()
Returns all non-overlapping matches of pattern in string, as a list of strings.
text = "The rain in Spain"
x = re.findall(r"ai", text)
print(x) # Output: ['ai', 'ai']Substitution
re.sub()
Replaces one or many matches with a string.
import re
text = "The rain in Spain"
# Replace white space with 9
x = re.sub(r"\s", "9", text)
print(x) # Output: The9rain9in9Spain