Lists & loops
Iterate, transform, and combine sequences with readable loop patterns.
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 Find the Third Smallest Element in a Python List
Find the third smallest distinct value in a Python list by sorting unique elements and returning the third index.
def find_third_smallest(numbers):
if len(numbers) < 3:
return None
unique_sorted = sorted(set(numbers))
if len(unique_sorted) < 3:
return None
return unique_sorted[2]
if __name__ == "__main__":
sample = [5, 2, 8, 2, 9, 1, 7, 3]
result = find_third_smallest(sampl…Browse by section
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Lists & loops — Python code examples
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This page collects lists & loops 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.