Why Do Python Sets Display Elements in a Seemingly Consistent Order?

Order of Elements in Python Sets

Sets in Python are unordered collections, meaning that the elements have no specific sequence. However, when the elements are displayed, a consistent order appears.

This order is determined by a hashing mechanism. Python hashes each element, takes the last few bits of the hash value, and uses them as an array index. The elements are then stored in memory in the order of their indices.

The subsequent display of the elements follows the order in which they are stored in memory. This order can differ from the original order in the input due to collisions in the hashing algorithm.

In the example:

set_1 = set([5, 2, 7, 2, 1, 88])
set_2 = set([5, 2, 7, 2, 1, 88])

The elements in both sets are the same, but the order may differ based on the specific bit positions used for hashing.

Additionally, the order of elements in the input list can influence the final order in the set. For example:

list1 = [8, 16, 24]
set(list1)        #set([8, 16, 24])
list2 = [24, 16, 8]
set(list2)        #set([24, 16, 8])

The resulting sets have different orders because the order of the input lists has changed.

It's important to note that the order of elements in sets is implementation-specific and may vary across different Python versions. While the general hashing mechanism is consistent, the details of how collisions are resolved and how elements are stored in memory can vary.

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