为什么dict（enumerate（example））返回一个随机字典？

Question

When I run this simple program:

example: {'left', 'right', 'up', 'down'}
new_dict = dict(enumerate(example))
print(new_dict)

each run results in a different (index, value) pair. For example:

MacBook-Air:Desktop mymac$ python3 example.py
{0: 'right', 1: 'down', 2: 'left', 3: 'up'}
MacBook-Air:Desktop mymac$ python3 example.py
{0: 'left', 1: 'up', 2: 'down', 3: 'right'}
MacBook-Air:Desktop mymac$ python3 example.py
{0: 'down', 1: 'left', 2: 'right', 3: 'up'}

Why is that?

Answer 1

from the docs https://docs.python.org/3/reference/datamodel.html#object. hash

Note By default, the __hash__() values of str , bytes and datetime objects are “salted” with an unpredictable random value. Although they remain constant within an individual Python process, they are not predictable between repeated invocations of Python.

Changing hash values affects the iteration order of dicts, sets and other mappings.

Changed in version 3.3: Hash randomization is enabled by default.