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I have some dictionary d.

k = d.keys()
v = d.values()

Is there a guarantee that k[n] and v[n] are related, for every n?

Tony Ennis
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3 Answers3

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According to this answer on a related question, dictionaries maintain insertion order as of Python 3.6. Here is a link to Guido's decree to "make it so".

Here is an example I did in the Python3 console to test that the relationship for every n is related:

>>> a = dict()
>>> a['yes'] = 'no'
>>> a['blah'] = 'beeper'
>>> a['foo'] = 'bar'
>>> a.keys()
dict_keys(['yes', 'blah', 'foo'])
>>> a.values()
dict_values(['no', 'beeper', 'bar'])
>>>

Edit: After reading some of the comments above, you would need to make these into lists to access them as indexes. So following that from the previous example:

>>> keys = list(a.keys())
>>> keys
['yes', 'blah', 'foo']
>>> values = list(a.values())
>>> values
['no', 'beeper', 'bar']
Milo Fultz
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Yes. Corresponding entries from .keys() and .values() represent the same key/value pair within the dictionary. (In older versions of Python, the orders may vary if you add or remove items, but they correspond if no such modifications are made between calls.)

d = {"answer": 42, "unlucky": 13, ...}
assert list(d.items()) == list(zip(d.keys(), d.values()))

This was made explicit in previous versions of the Python documentation. In recent versions of Python, where items retain their insertion order regardless of changes to the dictionary, they apparently didn't feel it needed to be made explicit, but it's still true.

Python dictionary: are keys() and values() always the same order?

kindall
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  • I think [the docs](https://docs.python.org/3/library/stdtypes.html#dictionary-view-objects) still make this fairly explicit: *"Keys and values are iterated over in insertion order. This allows the creation of (value, key) pairs using zip(): pairs = zip(d.values(), d.keys()). Another way to create the same list is pairs = [(v, k) for (k, v) in d.items()]."* – kaya3 Nov 08 '21 at 04:59
  • @kaya3 Aha, they changed the wording enough that my haphazard "Find in Page" didn't find it. :-) – kindall Nov 08 '21 at 14:58
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a = dict()
a["sas"] = 10
a["ase"] = 90
a["ing"] = 98
print(a)

And the keys on its own!

print(a[0])
print(a[1])
print(a[2])
gz200
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