Do Python's Dictionary Keys() and Values() Always Maintain a One-to-One Mapping?

Are Python's Dictionary Keys() and Values() Always in Sync?

In Python, dictionaries are powerful data structures that store key-value pairs. When retrieving the keys and values using the keys() and values() methods, it often appears that the resulting lists maintain a one-to-one mapping, as evident in the example below:

d = {'one': 1, 'two': 2, 'three': 3}
k, v = d.keys(), d.values()
for i in range(len(k)):
    print(d[k[i]] == v[i])

# Output: True
# True
# True

Maintaining Correspondence

However, is it guaranteed that this one-to-one mapping will persist even if the dictionary undergoes modifications? According to the Python documentation for both Python 2.x and 3.x, this is indeed the case:

"If items(), keys(), values(), iteritems(), iterkeys(), and itervalues() are called with no intervening modifications to the dictionary, the lists will directly correspond."

Therefore, it is safe to assume that the above for-loop will always print True, provided that the dictionary does not change between the calls to keys() and values(). This correspondence between keys and values in dictionary iteration is a valuable aspect of Python's dictionary implementation, providing predictable and efficient access to the stored data.

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