Lists & loops
Iterate, transform, and combine sequences with readable loop patterns.
Find Most Active Contributors in a Repository with Python
Filter recent commits by date and count the most active contributors using Counter and datetime.
from collections import Counter
from datetime import datetime, timedelta
# Simulated commit data
commits = [
{"author": "Alice", "timestamp": datetime.now() - timedelta(days=1)},
{"author": "Bob", "timestamp": datetime.now() - timedelta(days=2)},
{"author": "Alice", "timestamp": datetime.now() - timedelta…Generate Data Helper for Beginners in Python
Define two functions that create a random list of integers and then compute basic summary statistics like count, total, average, maximum, and minimum using simple loops.
from random import randint
def build_dataset(size: int, max_val: int) -> list[int]:
data = []
for _ in range(size):
data.append(randint(1, max_val))
return data
def summarize(data: list[int]) -> dict[str, float]:
total = 0
maximum = data[0]
minimum = data[0]
for value in data:
…How to Build a Frequency Map from a List in Python
This code builds a dictionary that maps each unique element in a list to its count using the Counter class from the collections module.
from collections import Counter
def build_frequency_map(values):
"""Return a dictionary mapping each unique value to its frequency."""
return dict(Counter(values))
if __name__ == "__main__":
data = ["apple", "banana", "apple", "cherry", "banana", "apple"]
freq_map = build_frequency_map(data)
prin…How to Build a Text Processor with Lists and Loops in Python
A beginner-friendly Python script that analyzes text by counting sentences, words, and word lengths using lists and for loops, then prints the results.
def process_text(text):
"""Simple text processor for beginners using lists and loops."""
sentences = text.replace('!', '.').replace('?', '.').split('.')
words = text.split()
word_counts = []
for sentence in sentences:
sentence_word_count = len(sentence.split())
word_counts.appe…How to Count Occurrences of a Value in a Python List
Counts how many times a specific value appears in a list using a simple loop and a counter variable.
def count_occurrences(data, target):
count = 0
for item in data:
if item == target:
count += 1
return count
if __name__ == "__main__":
numbers = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5]
target_value = 5
result = count_occurrences(numbers, target_value)
print(f"The value {targ…How to Count, Double, and Find Max in a Python List
Three beginner-friendly Python functions that count even numbers, double each value, and find the maximum in a list using simple loops.
def count_even_numbers(numbers):
"""Return the count of even numbers in a list."""
count = 0
for num in numbers:
if num % 2 == 0:
count += 1
return count
def double_values(numbers):
"""Return a new list with each value doubled."""
doubled = []
for num in numbers:
…How to Filter a List in Python with a Loop
Filter a list of numbers by a threshold using a for loop and append results to a new list, then print the filtered values and count.
ages = [34, 12, 45, 8, 67, 21, 18, 55, 3]
threshold = 18
adults = []
for age in ages:
if age >= threshold:
adults.append(age)
print("All ages:", ages)
print("Adults (18+):", adults)
print("Count of adults:", len(adults))How to Find the Mode in a Python List
Find the most frequent value (mode) in a Python list using the collections.Counter class, handling empty lists and ties.
from collections import Counter
def find_mode(numbers):
if not numbers:
return None
counts = Counter(numbers)
max_count = max(counts.values())
modes = [num for num, count in counts.items() if count == max_count]
return modes[0] if len(modes) == 1 else modes
if __name__ == "__main__":
…How to Process Text Lines with Lists and Loops in Python
This code processes a list of text lines by stripping whitespace, converting to uppercase, and reporting character counts per line and totals.
def process_text(lines):
"""Convert a list of text lines to uppercase and report line statistics."""
processed = []
total_chars = 0
for index, line in enumerate(lines, start=1):
cleaned = line.strip().upper()
processed.append(cleaned)
total_chars += len(cleaned)
pri…How to Process Text with Lists and Loops in Python
A beginner-friendly text processor that splits a sentence into words, filters by length, counts vowels, and reports results using lists and loops.
text = "Python makes text processing easy and fun"
words = text.lower().split()
print("Words in the sentence:")
for index, word in enumerate(words, start=1):
print(f"{index}. {word}")
filtered_words = [word for word in words if len(word) > 3]
print(f"\nWords longer than 3 characters: {filtered_words}")
letter…How to Process Text with Lists and Loops in Python
Iterate over a list of text lines to count words, show uppercase versions, and report character counts per line.
# text_processor.py
def process_text(lines):
"""Count words, show uppercase, and count characters per line."""
total_words = 0
print("Line-by-line analysis:")
for i, line in enumerate(lines, start=1):
words = line.split()
total_words += len(words)
print(f" Line {i}: {len(words…How to Summarize a List of Numbers in Python
Loop over a list of numbers to compute total, count, average, min, and max, then return them in a dictionary.
def summarize_numbers(numbers):
"""Return a dict with basic stats for a list of numbers."""
total = 0
count = 0
smallest = numbers[0]
largest = numbers[0]
for num in numbers:
total += num
count += 1
if num < smallest:
smallest = num
if num > largest:…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):
…Truncate List Keeping Last N Elements in Python
Return a new list containing only the last N elements from a sequence, handling edge cases like zero or oversized counts.
def truncate(seq, keep_last_n):
"""Return a new list keeping only the last n elements."""
if keep_last_n <= 0:
return []
return list(seq)[-keep_last_n:]
if __name__ == "__main__":
data = [10, 20, 30, 40, 50, 60]
print(truncate(data, 3))
print(truncate(data, 0))
print(truncate(data…Browse by section
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Lists & loops — Python code examples
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