Common list elements: Difference between revisions
A Python implementation
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{3,9,6}
{2,3,6}
</pre>
=={{header|Python}}==
===Without Duplicates===
<lang python>"""Find distinct common list elements using set.intersection."""
def common_list_elements(*lists):
return list(set.intersection(*(set(list_) for list_ in lists)))
if __name__ == "__main__":
test_cases = [
([2, 5, 1, 3, 8, 9, 4, 6], [3, 5, 6, 2, 9, 8, 4], [1, 3, 7, 6, 9]),
([2, 2, 1, 3, 8, 9, 4, 6], [3, 5, 6, 2, 2, 2, 4], [2, 3, 7, 6, 2]),
]
for case in test_cases:
result = common_list_elements(*case)
print(f"Intersection of {case} is {result}")
</lang>
{{out}}
<pre>
intersection of ([2, 5, 1, 3, 8, 9, 4, 6], [3, 5, 6, 2, 9, 8, 4], [1, 3, 7, 6, 9]) is [9, 3, 6]
intersection of ([2, 2, 1, 3, 8, 9, 4, 6], [3, 5, 6, 2, 2, 2, 4], [2, 3, 7, 6, 2]) is [2, 3, 6]
</pre>
===With Duplicates===
<lang python>"""Find common list elements using collections.Counter (multiset)."""
from collections import Counter
from functools import reduce
from itertools import chain
def common_list_elements(*lists):
counts = (Counter(list_) for list_ in lists)
intersection = reduce(lambda x, y: x & y, counts)
return list(chain.from_iterable([elem] * cnt for elem, cnt in intersection.items()))
if __name__ == "__main__":
test_cases = [
([2, 5, 1, 3, 8, 9, 4, 6], [3, 5, 6, 2, 9, 8, 4], [1, 3, 7, 6, 9]),
([2, 2, 1, 3, 8, 9, 4, 6], [3, 5, 6, 2, 2, 2, 4], [2, 3, 7, 6, 2]),
]
for case in test_cases:
result = common_list_elements(*case)
print(f"Intersection of {case} is {result}")
</lang>
{{out}}
<pre>
intersection of ([2, 5, 1, 3, 8, 9, 4, 6], [3, 5, 6, 2, 9, 8, 4], [1, 3, 7, 6, 9]) is [9, 3, 6]
intersection of ([2, 2, 1, 3, 8, 9, 4, 6], [3, 5, 6, 2, 2, 2, 4], [2, 3, 7, 6, 2]) is [2, 2, 3, 6]
</pre>
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