Strings & text
Format, split, join, parse, and clean text — everyday Python string patterns.
Automatically Detect Weak Passwords from Large Password Lists in Python
This Python script identifies weak passwords from a list by checking length, common patterns, sequential characters, and uniform characters, returning those that fail the security checks.
import re
COMMON_PASSWORDS_FILE = "common_passwords.txt"
def is_weak(password):
# Check length
if len(password) < 8:
return True
# Check for common patterns
if password.lower() in {"password", "123456", "qwerty", "letmein", "admin", "welcome"}:
return True
# Check for sequential c…Build CSV row from Python list with proper quoting
Converts a list of fields into a properly quoted CSV row string using the csv module.
import csv
import io
def build_csv_row(fields):
output = io.StringIO()
writer = csv.writer(output)
writer.writerow(fields)
return output.getvalue().rstrip("\r\n")
if __name__ == "__main__":
fields = ["Alice", "Smith", "123 Main St, Apt 4B", "alice@example.com"]
print(build_csv_row(fields))Extract Data from Strings in Python: Beginner's Guide
A beginner-friendly helper that splits a comma-separated string into a list, shows word count, and extracts the first and last words using Python's split() and join() methods.
text = "python,string,extract,beginner"
words = text.split(",")
print("Full text:", text)
print("Word count:", len(words))
print("First word:", words[0])
print("Last word:", words[-1])
joined = " | ".join(words)
print("Joined with separator:", joined)Extract Email-Like Tokens from Text in Python
Uses a regular expression to find all email-like tokens in a string, returning them as a list with re.findall.
import re
def extract_email_like_tokens(text):
pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b'
return re.findall(pattern, text)
if __name__ == "__main__":
sample_text = (
"Contact us at support@example.com or sales@company.co.uk. "
"Invalid: hello@world, user@.com, test@do…Extract URLs from text with regex in Python
Uses a regular expression to find and print HTTP/HTTPS URLs from a block of text.
import re
text = """
Visit https://www.example.com for docs.
Contact support@mysite.org.
Check http://localhost:8000/api or ftp://files.example.net.
"""
url_pattern = r'https?://[^\s]+'
urls = re.findall(url_pattern, text)
for url in urls:
print(url)Find Data From a String in Python: Stats, Clean, Keywords
Three helper functions for beginners: compute character/word/sentence stats, normalize whitespace and case, and extract unique sorted keywords from a string.
def get_text_stats(text):
"""Return basic statistics about a string."""
words = text.split()
sentences = text.replace('!', '.').replace('?', '.').split('.')
sentences = [s for s in sentences if s.strip()]
return {
'characters': len(text),
'words': len(words),
'sentences': le…How to Extract Digits Only from a String in Python
This code uses a regular expression to remove all non-digit characters from a mixed string, returning only the digits.
import re
def extract_digits(text):
"""Return only the digits from the given text as a string."""
return re.sub(r'\D', '', text)
if __name__ == "__main__":
mixed = "abc123def456!@#789"
result = extract_digits(mixed)
print(result)How to Generate Initials from a Full Name in Python
Extract and uppercase the first letter of each word in a full name to produce initials using standard string methods.
def generate_initials(full_name):
parts = full_name.strip().split()
initials = ''.join(part[0].upper() for part in parts if part)
return initials
if __name__ == "__main__":
name = "john f. kennedy"
print(generate_initials(name))How to Join Multiline Text with a Semicolon Separator in Python
This code joins non-empty lines of multiline text into a single string separated by semicolons, stripping leading and trailing whitespace from each line.
def join_multiline_text_with_semicolon(text):
"""Join lines of multiline text with a semicolon separator."""
lines = [line.strip() for line in text.splitlines() if line.strip()]
return "; ".join(lines)
if __name__ == "__main__":
sample_text = """First line
Second line
Third line"""
result = join_…How to Merge Two Strings Character by Character in Python
Interleave characters from two strings, appending any surplus characters from the longer string at the end.
def merge_texts(left: str, right: str) -> str:
"""
Merges two strings by interleaving their characters:
first char from left, first from right, then second from left,
second from right, and so on. If one string is longer, the
remaining characters are appended at the end.
Example:
merge_tex…How to Remove HTML Tags in Python with Regex
Strips all HTML tags from a string using a regular expression and cleans extra whitespace.
import re
def remove_html_tags(text: str) -> str:
"""Remove all HTML tags from the given text using regex."""
# Remove opening and closing tags
clean = re.sub(r'<[^>]+>', '', text)
# Remove any extra whitespace left behind
clean = re.sub(r'\s+', ' ', clean).strip()
return clean
if __name__ ==…How to Strip Whitespace in Python
This code demonstrates how to remove leading and trailing whitespace from a string using the built-in strip() method.
def strip_whitespace(text: str) -> str:
return text.strip()
if __name__ == "__main__":
sample = " Hello, world! "
result = strip_whitespace(sample)
print(f"Original: '{sample}'")
print(f"Stripped: '{result}'")How to remove punctuation from a string in Python
Remove all punctuation characters from a string using the str.translate method and string.punctuation from the standard library.
import string
def remove_punctuation(text: str) -> str:
return text.translate(str.maketrans("", "", string.punctuation))
if __name__ == "__main__":
sample = "Hello, world! It's a test... (with punctuation) - done?"
cleaned = remove_punctuation(sample)
print(f"Original: {sample}")
print(f"Cleaned:…Python String Helper Functions for Beginners
A set of beginner-friendly Python functions that count words, reverse text, convert to title case, strip punctuation, and compute character frequency from a string.
def count_words(text):
"""Count the number of words in a string."""
return len(text.split())
def reverse_text(text):
"""Reverse the entire string."""
return text[::-1]
def title_case(text):
"""Capitalize the first letter of each word."""
return text.title()
def remove_punctuation(text):
…Remove Substring Occurrences Case-Insensitively in Python
This code removes every case-insensitive occurrence of a given substring from a text string using a simple looping approach.
def remove_occurrences_ci(text: str, substring: str) -> str:
"""Remove all case-insensitive occurrences of substring from text."""
if not substring:
return text
result = []
i = 0
lower_text = text.lower()
lower_sub = substring.lower()
sub_len = len(substring)
while i <…String helpers in Python: stats, reverse, and remove vowels
Three beginner-friendly Python functions compute text statistics, reverse word order, and strip vowels from a string.
def text_stats(text: str) -> dict:
"""Return basic statistics for a given text string."""
words = text.split()
return {
"characters": len(text),
"words": len(words),
"sentences": text.count(".") + text.count("!") + text.count("?"),
"uppercase": sum(1 for c in text if c.isupp…Browse by section
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Strings & text — Python code examples
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This page collects strings & text snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
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Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.