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How to Validate Text Against Forbidden Words in Python
Checks whether a given text contains any forbidden words and returns a tuple with validity and offending words.
def validate_text(text, forbidden_words):
"""
Checks that text does not contain any forbidden words.
Returns (is_valid, offending_words) tuple.
"""
words = text.lower().split()
found = [word for word in words if word in forbidden_words]
return len(found) == 0, found
if __name__ == "__main…How to Zip Two Lists into Pairs in Python
Combine two lists element-wise into a list of tuples using Python's built-in zip() function.
def zip_lists_into_pairs(list1, list2):
pairs = list(zip(list1, list2))
return pairs
if __name__ == "__main__":
fruits = ["apple", "banana", "cherry"]
quantities = [3, 5, 2]
result = zip_lists_into_pairs(fruits, quantities)
print(result)How to check list items by type and emptiness in Python
Loop through a list with enumerate(), classify each item as empty, number, or text, and print a formatted status for each element.
def check_data(data):
"""Check each item in a list and print whether it's valid."""
for i, item in enumerate(data):
if item is None or item == "":
status = "empty"
elif isinstance(item, (int, float)):
status = "number"
else:
status = "text"
pr…How to split a list by condition in Python
Splits a list into two lists based on a condition function, returning matched and unmatched items.
def split_by_condition(items, condition):
"""
Split a list into two lists based on a condition.
The first list contains items where condition(item) is True,
the second list contains the rest.
"""
matched = []
unmatched = []
for item in items:
if condition(item):
matc…How to summarize and transform lists in Python
Compute count, sum, min, max, and average for a list and multiply each element by a factor using simple loops and built-in functions.
def summarize(data):
"""Return a summary of a list: count, sum, min, max, average."""
count = len(data)
total = sum(data)
minimum = min(data)
maximum = max(data)
average = total / count if count else 0
return count, total, minimum, maximum, average
def multiply_elements(data, factor=2):
…How to unzip a list of pairs into two lists in Python
Split a list of (a, b) tuples into two separate lists by iterating with a for loop and appending each element to its own output list.
def unzip(pairs):
"""Split a list of (a, b) pairs into two separate lists."""
if not pairs:
return [], []
firsts = []
seconds = []
for a, b in pairs:
firsts.append(a)
seconds.append(b)
return firsts, seconds
if __name__ == "__main__":
pairs = [(1, 'a'), (…Intersection of Two Lists Preserving Order in Python
This code returns the common elements between two lists while preserving the order they appear in the first list, filtering out duplicates.
def intersection_preserving_order(list1, list2):
"""
Return the intersection of two lists while preserving the order
of elements as they appear in list1.
"""
set2 = set(list2)
result = []
seen = set()
for item in list1:
if item in set2 and item not in seen:
resu…Round Robin Merge Multiple Lists in Python
Merge multiple lists by taking one element from each in turn, stopping when all lists are exhausted.
from itertools import cycle
def round_robin_merge(*lists):
"""Merge multiple lists by taking one element from each in turn."""
result = []
max_len = max(len(lst) for lst in lists)
for i in range(max_len):
for lst in lists:
if i < len(lst):
result.append(lst[i])…Separate Evens and Odds into Two Lists in Python
Split a list of numbers into two lists containing even and odd numbers using a simple loop and the modulo operator.
def separate_evens_odds(numbers):
evens = []
odds = []
for num in numbers:
if num % 2 == 0:
evens.append(num)
else:
odds.append(num)
return evens, odds
if __name__ == "__main__":
nums = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
evens, odds = separate_evens_odds(nu…Symmetric difference between two lists in Python
Find elements present in exactly one of two lists, preserving original order, with a simple Python function.
def symmetric_difference(list1, list2):
"""
Return the symmetric difference of two lists.
Elements present in exactly one of the lists, preserving order.
"""
set1 = set(list1)
set2 = set(list2)
# Elements in list1 but not in list2
diff1 = [x for x in list1 if x not in set2]
# E…How to Merge Lists in Python with Default Parameters
This Python function merges two lists using the + operator and demonstrates default parameters, allowing the second argument to be omitted.
def merge_lists(list1, list2=["default"]):
"""Merge two lists and return the combined result."""
return list1 + list2
if __name__ == "__main__":
# Example with default parameter
print("With default:", merge_lists([1, 2, 3]))
# Example with both arguments provided
print("With custom:", me…How to Sort a List of Numbers in Python with Default Parameters
Define a reusable sort function that uses a default parameter to sort a list of numbers in ascending or descending order.
def sort_numbers(numbers, reverse=False):
"""Sort a list of numbers in ascending or descending order."""
return sorted(numbers, reverse=reverse)
def main():
numbers = [5, 2, 9, 1, 7, 3]
# Default sort (ascending)
ascending = sort_numbers(numbers)
print(f"Ascending: {ascending}")
…How to Use Lambda Sorting Keys in Python
Learn to sort lists of dictionaries using lambda functions as key arguments in Python's sorted() method.
# Demonstrate lambda as a sorting key function
students = [
{"name": "Alice", "grade": 88},
{"name": "Bob", "grade": 92},
{"name": "Charlie", "grade": 75},
{"name": "Diana", "grade": 95}
]
# Sort by grade (ascending) using a lambda key
sorted_by_grade = sorted(students, key=lambda student: student["g…How to Use functools.reduce in Python
Apply functools.reduce with operator functions and lambda expressions to aggregate lists into sums, products, maximums, and concatenated strings.
from functools import reduce
import operator
# Sum all numbers in a list using reduce
numbers = [1, 2, 3, 4, 5]
sum_result = reduce(operator.add, numbers)
# Find the maximum value using reduce
max_result = reduce(lambda a, b: a if a > b else b, numbers)
# Multiply all numbers using reduce
product_result = reduce(la…How to Mock a Failing Dependency to Test Error Paths in Python
Inject a fake HTTP client that raises a connection error to test how code handles dependency failures without touching the network.
import requests
def fetch_user(user_id):
url = f"https://api.example.com/users/{user_id}"
response = requests.get(url, timeout=5)
response.raise_for_status()
return response.json()
def get_user_name(user_id, http_client):
try:
user_data = http_client(user_id)
return user_data["nam…Use pprint for Nested Structure Debug Output in Python
Pretty-print nested dictionaries and lists with pprint for readable, organized debug output.
from pprint import pprint
def build_nested_structure():
"""Create a sample nested data structure for demonstration."""
return {
"project": "DataPipeline",
"config": {
"inputs": ["raw_1.json", "raw_2.json"],
"processing": {
"steps": ["clean", "transform",…How to Delete a File if it Exists in Python
Delete a file safely in Python using pathlib's Path.unlink, checking existence first to avoid errors.
from pathlib import Path
def delete_file_if_exists(file_path: str) -> bool:
"""Delete a file if it exists. Returns True if deleted, False if not found."""
path = Path(file_path)
if path.exists():
path.unlink()
print(f"Deleted: {path}")
return True
else:
print(f"File not…How to check file data in Python
Check if a file exists and is a regular file, then return its name, size, line count, and first line.
def check_file_data(file_path):
from pathlib import Path
path = Path(file_path)
if not path.exists():
return f"File '{file_path}' does not exist."
if not path.is_file():
return f"'{file_path}' is not a regular file."
size = path.stat().st_size
lines = path.read_text(encodin…Convert Lists and Dictionaries to Sets in Python
Convert lists of pairs into dictionaries and lists or dictionaries into sets using simple helper functions.
def convert_to_dict(data):
"""Convert list of tuples or lists into a dictionary."""
return dict(data)
def convert_to_set(data):
"""Convert list or dictionary into a set of its keys/values."""
if isinstance(data, dict):
return set(data.keys())
return set(data)
def convert_collection(data…How to Count Word Frequencies in Python with Counter and Sets
This code processes a text string by lowercasing, splitting into words, counting frequencies with Counter, and extracting unique and sorted word lists using sets.
from collections import Counter
def process_text(text):
words = text.lower().split()
word_counts = Counter(words)
unique_words = set(words)
sorted_words = sorted(unique_words)
return {
"total_words": len(words),
"unique_words": len(unique_words),
"word_frequencies": di…How to Create a Dict from Two Parallel Lists in Python (zip)
Build a dictionary by pairing elements from two parallel lists using Python's built-in zip function and dict constructor.
keys = ["name", "age", "city"]
values = ["Alice", 30, "New York"]
result = dict(zip(keys, values))
print(result)How to Group a List of Dictionaries by Key in Python
Group a list of dictionaries by a specified key field using dict.setdefault to build a dictionary of lists.
def group_by_key(records, key):
grouped = {}
for record in records:
grouped.setdefault(record[key], []).append(record)
return grouped
if __name__ == "__main__":
data = [
{"name": "Alice", "dept": "engineering"},
{"name": "Bob", "dept": "sales"},
{"name": "Carol", "dept"…How to Parse Data Into Dictionaries and Sets in Python
Parses raw student strings into a dictionary of lists and finds unique courses using a set.
from collections import defaultdict
def parse_students(raw_data):
"""Parse raw student strings into a dictionary of lists."""
parsed = defaultdict(list)
for entry in raw_data:
name, _, course = entry.partition(":")
parsed[course.strip()].append(name.strip())
return dict(parsed)
def fi…How to Parse Query String to Dict with Duplicate Keys in Python
Convert a URL query string into a Python dictionary, merging duplicate keys into lists while keeping single values as scalars.
from urllib.parse import parse_qs
def parse_query_to_dict(query_string):
parsed = parse_qs(query_string, keep_blank_values=True)
return {key: values if len(values) > 1 else values[0] for key, values in parsed.items()}
if __name__ == "__main__":
query = "name=John&name=Jane&age=30&city=&city=Paris&empty…Browse by section
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