Check for URL in a String - Python

We are given a string that may contain one or more URLs and our task is to extract them efficiently. This is useful for web scraping, text processing, and data validation. For example:

Input:

s = "My Profile: https://www.geeksforgeeks.org/user/Prajjwal%20/contributions/ in the portal of https://www.geeksforgeeks.org/"

Output:

['https://www.geeksforgeeks.org/404.html/', 'https://www.geeksforgeeks.org/']

Using re.findall()

Python’s Regular Expressions (regex) module allows us to extract patterns like URLs from texts, it comes with various functions like findall(). The re.findall() function in Python is used to find all occurrences of a pattern in a given string and return them as a list.

import re

s = 'My Profile: https://www.geeksforgeeks.org/404.html/ in the portal of https://www.geeksforgeeks.org/'
pattern = r'https?://\S+|www\.\S+'

print("URLs:", re.findall(pattern, s))

URLs: ['https://www.geeksforgeeks.org/404.html/', 'https://www.geeksforgeeks.org/']

Explanation:

• r'https?://\S+|www\.\S+' is a regex pattern to match URLs starting with http://, https://, or www.
• findall() extracts all matches in a list.

Using the urlparse()

urlparse() function from Python's urllib.parse module helps break down a URL into its key parts, such as the scheme (http, https), domain name, path, query parameters, and fragments. This function is useful for validating and extracting URLs from text by checking if a word follows a proper URL structure.

from urllib.parse import urlparse

s = 'My Profile: https://www.geeksforgeeks.org/404.html/ in the portal of https://www.geeksforgeeks.org/'

# Split the string into words
split_s = s.split()

# Empty list to collect URLs
urls = []
for word in split_s:
    parsed = urlparse(word)
    if parsed.scheme and parsed.netloc:
        urls.append(word)

print("URLs:", urls)

URLs: ['https://www.geeksforgeeks.org/404.html/', 'https://www.geeksforgeeks.org/']

Explanation:

• s.split() function splits the string to words.
• then urlparse(word) function checks each word to see if it has a valid scheme (http/https) and domain.
• URLs are added to url list using append() function.

Using urlextract()

urlextract is a third party library so to use it we need to first install it by giving the command "pip install urlextract" in out terminal, it offers a pre-built solution to find URLs in text. Its URLExtract class helps us to quickly identify URLs without needing custom patterns, making it a convenient choice for difficult extraction of URLs.

from urlextract import URLExtract

s = 'My Profile: https://www.geeksforgeeks.org/user/Prajjwal%20/contributions/ in the portal of https://www.geeksforgeeks.org/'
extractor = URLExtract()
urls = extractor.find_urls(s)

print("URLs:", urls)

Urls:  ['https://www.geeksforgeeks.org/user/Prajjwal%20/contributions/', 'https://www.geeksforgeeks.org/']

Explanation:

• import URLExtract from the urlextract library.
• URLExtract() creates an extractor object to scan the string.
• find_urls() detects all URLs in s and returns them as a list, no manual splitting or validation is needed.

Using startswith()

One simple approach is to split the string and check if each word starts with "https://" or "https://" using .startswith() built-in method, we can use .split() function to split the string and then check each word, if it starts with "https://" or "https://". If it does, we add it to our list of extracted URLs.

s = 'My Profile: https://www.geeksforgeeks.org/404.html/ in the portal of https://www.geeksforgeeks.org/'
x = s.split()

# Empty list to extract the URL
res=[]

for i  in x:
    if i.startswith("https:") or i.startswith("http:"):
        res.append(i)  
        
print("Urls: ", res)

Urls:  ['https://www.geeksforgeeks.org/404.html/', 'https://www.geeksforgeeks.org/']

Explanation:

• string.split() method splits the string into words.
• then we checks if each word starts with http:// or https:// using the "if" statement.
• if it does, then we add it to the list of URLs using .append() method.

Using find() method

find() is a built-in method in Python that is used to find a specific element in a collection, so we can use it to identify and extract a URL from a string. Here's how:

s = 'My Profile: https://www.geeksforgeeks.org/404.html/ in the portal of https://www.geeksforgeeks.org/'
split_s = s.split()

res=[]

for i in split_s:
    if i.find("https:")==0 or i.find("http:")==0:
        res.append(i)

print("Urls: ", res)

Urls:  ['https://www.geeksforgeeks.org/404.html/', 'https://www.geeksforgeeks.org/']

Explanation:

• s.split() funtion splits the string to words.
• identify url using i.find() function.
• add the URLs to the list 'res' using .append().

Related Articles:

• Regex Tutorial
• re.findall() in Python
• Python Urllib Module
• Python List append() Method
• Python – String startswith()
• Python String split()
• Python String find() Method