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Finding Common Values in Two Python Lists

TECHNOLOGY

In daily life, we often encounter the need to find common values between two arrays. This article provides several simple and practical methods on how to elegantly get common values between two arrays in Python.

1. Using the & operator with sets

list1 = [1,2,3,4,5,6,7]
list2 = [1,3, 5, 7, 9]
set(list1) & set(list2)
#{1, 3, 5, 7}

2. Using the intersection() method with sets

list1 = [1,2,3,4,5,6,7]
list2 = [1,3, 5, 7, 9]
set(list1).intersection(list2)
#{1, 3, 5, 7}

3. Brute-force checking if an element from the first list is in the second list

list1 = [1,2,3,4,5,6,7]
list2 = [1,3, 5, 7, 9]
[element for element in list1 if element in list2]
   # [1, 3, 5, 7]

4. Using set subtraction

list1 = [1,2,3,4,5,6,7]
list2 = [1,3, 5, 7, 9]
set(list1) - (set(list1)-set(list2))
#{1, 3, 5, 7}

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