Section 1.1: The search() Method

The search() function identifies the first instance of a specified pattern within a string.

Simple example:

import re

string = "The quick brown fox jumps over the lazy dog"

match = re.search(r"fox", string)

print(match.group(0)) # Output: "fox"

Complex example:

import re

string = "Timestamp: 2021-05-01 12:34:56.789"

match = re.search(r"(d{4}-d{2}-d{2}) (d{2}:d{2}:d{2}.d{3})", string)

print(match.group(1)) # Output: "2021-05-01"

print(match.group(2)) # Output: "12:34:56.789"

Section 1.2: The findall() Method

The findall() method retrieves all non-overlapping matches of a pattern in a string.

Simple example:

import re

string = "The quick brown fox jumps over the lazy dog"

matches = re.findall(r"w{4}", string)

print(matches) # Output: ['quick', 'brown', 'jumps', 'over', 'lazy', 'dog']

Complex example:

import re

string = "Timestamp: 2021-05-01 12:34:56.789nTimestamp: 2022-06-02 11:22:33.444"

matches = re.findall(r"(d{4}-d{2}-d{2}) (d{2}:d{2}:d{2}.d{3})", string)

print(matches) # Output: [('2021-05-01', '12:34:56.789'), ('2022-06-02', '11:22:33.444')]

Section 1.3: The split() Method

The split() function divides a string into a list based on a specified delimiter.

Simple example:

import re

string = "The,quick,brown,fox,jumps,over,the,lazy,dog"

words = re.split(r",", string)

print(words) # Output: ['The', 'quick', 'brown', 'fox', 'jumps', 'over', 'the', 'lazy', 'dog']

Complex example:

import re

string = "Timestamp: 2021-05-01 12:34:56.789nTimestamp: 2022-06-02 11:22:33.444"

matches = re.split(r"(d{4}-d{2}-d{2}) (d{2}:d{2}:d{2}.d{3})", string)

print(matches) # Output: ['Timestamp: ', '2021-05-01', ' 12:34:56.789nTimestamp: ', '2022-06-02', '11:22:33.444']

Section 1.4: The sub() Method

The sub() method replaces occurrences of a pattern in a string with a designated replacement.

Simple example:

import re

string = "The quick brown fox jumps over the lazy dog"

new_string = re.sub(r"fox", "cat", string)

print(new_string) # Output: "The quick brown cat jumps over the lazy dog"

Complex example:

import re

string = "Timestamp: 2021-05-01 12:34:56.789nTimestamp: 2022-06-02 11:22:33.444"

new_string = re.sub(r"(d{4}-d{2}-d{2}) (d{2}:d{2}:d{2}.d{3})", r"1T2", string)

print(new_string) # Output: "Timestamp: 2021-05-01T12:34:56.789nTimestamp: 2022-06-02T11:22:33.444"

Section 1.5: The compile() Method

The compile() method compiles a regex pattern into a regex object for matching against multiple strings.

Simple example:

import re

pattern = re.compile(r"fox")

string = "The quick brown fox jumps over the lazy dog"

match = pattern.search(string)

print(match.group(0)) # Output: "fox"

Complex example:

import re

pattern = re.compile(r"(d{4}-d{2}-d{2}) (d{2}:d{2}:d{2}.d{3})")

string1 = "Timestamp: 2021-05-01 12:34:56.789"

string2 = "Timestamp: 2022-06-02 11:22:33.444"

match1 = pattern.search(string1)

match2 = pattern.search(string2)

print(match1.group(1)) # Output: "2021-05-01"

print(match2.group(2)) # Output: "11:22:33.444"

These methods can be utilized in various scenarios depending on your needs. The examples provided illustrate the fundamental usage of each method, but for further details, refer to the official Python documentation for the 're' module.

Section 1.6: Video Tutorial on Using the re Module

For an in-depth look at using the Python re module for regular expressions, watch the following tutorial.

Feel free to delve deeper into regex processing and enhance your programming skills!