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Python Code Samples

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4 matches
Lists & loops easy

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.

lists intersection order
Python
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…
15 0 Open
Dictionaries & sets easy

How to Find the Intersection of Permission Sets in Python

This code defines a function that takes a list of permission sets and returns a set containing only the permissions common to all sets, with a short-circuit for empty results.

sets intersection permissions
Python
from typing import Set

def intersect_permissions(permission_sets: list[Set[str]]) -> Set[str]:
    """
    Given a list of permission sets, return the common permissions
    present in every set.
    """
    if not permission_sets:
        return set()
    
    common = permission_sets[0]
    for perm_set in permissi…
12 0 Open
Algorithms & data structures easy

Find Common Elements in List of Lists in Python

Return elements that appear in every sublist of a nested list, preserving duplicates with Counter intersection.

counter intersection nested-lists
Python
from collections import Counter


def common_elements(list_of_lists):
    """Return elements present in every sublist."""
    if not list_of_lists:
        return []
    counts = Counter(list_of_lists[0])
    for sublist in list_of_lists[1:]:
        counts &= Counter(sublist)
    return list(counts.elements())


if _…
14 0 Open
Algorithms & data structures easy

How to Compute Jaccard Similarity in Python

Compute the Jaccard similarity between two lists by converting them to sets and dividing the intersection size by the union size.

jaccard sets similarity
Python
def jaccard_similarity(list1, list2):
    set1 = set(list1)
    set2 = set(list2)
    
    intersection = set1 & set2
    union = set1 | set2
    
    if not union:
        return 0.0
    
    return len(intersection) / len(union)

if __name__ == "__main__":
    a = [1, 2, 3, 4, 5]
    b = [3, 4, 5, 6, 7]
    
    pri…
17 0 Open

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