Functions & basics
Reusable building blocks — parameters, returns, scope, and clear function design.
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 Dictionaries by Key with a Lambda in Python
Sort a list of dictionaries ascending or descending by one of their keys using sorted() with a lambda as the key function — a beginner-friendly pattern.
def get_students():
return [
{"name": "alice", "score": 85},
{"name": "bob", "score": 92},
{"name": "carol", "score": 78},
{"name": "dave", "score": 92},
]
students = get_students()
sorted_by_score = sorted(students, key=lambda s: s["score"])
print("Sorted by score (ascending)…How to Use Default Parameters in Python Functions
A beginner-friendly Python function that uses default parameters to compare two numbers with equal, greater, or less operations.
def compare(a, b, operation="equal"):
if operation == "equal":
return a == b
elif operation == "greater":
return a > b
elif operation == "less":
return a < b
else:
return f"Unknown operation: {operation}"
if __name__ == "__main__":
print(compare(5, 5))
print(com…How to Use Default Parameters with Python's Split Function
Create a reusable Python wrapper around str.split with sensible default parameters for delimiter and maxsplit, showing beginners how default arguments work.
def split_with_defaults(text, delimiter=" ", maxsplit=-1):
"""
Split a string into parts using a delimiter.
Default behavior: split on spaces, unlimited splits.
"""
parts = text.split(delimiter, maxsplit)
return parts
if __name__ == "__main__":
# Example usage with defaults and custom par…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…Python Filter Function with Default Parameters for Beginners
Create a reusable filter function with default parameters to keep or exclude numbers above or below a threshold.
def filter_numbers(numbers, threshold=0, reverse=False):
"""Return numbers that pass the threshold filter.
Args:
numbers: list of numbers to filter
threshold: minimum value to keep (default 0)
reverse: if True, keep numbers below threshold (default False)
"""
if reverse:
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This page collects functions & basics 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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