Retrieve first key-value pair from a dictionary in Python without using list, iter

Question

In case I have a huge dictionary my_dict with a complex structure.

my_dict = {'complex_key': ('complex', 'values')}

If I want to see its first key-value pair (to understand whats inside), currently I use:

list(my_dict.items())[0]

However, this dublicates all the keys in the memory. It is also inconvienient, because pdb.set_trace() does not execute expressions starting with list . It is possible to use iterator:

next(iter(my_dict.items()))

However, its inconvenient, because I cannot access n'th element easily.

Is there any other easy way to access key-value pairs of dict_items() ?

In Python 2.7 this expression used to work:

my_dict.items()[0]

Update Ended up using:

tuple(my_dict.items())[0]

This approach at least overcomes the pdb.set_trace() limitation. It also allows to easily access n'th element and does not require any imports like from itertools import islice .

Answer 1

The reason my_dict.items()[0] worked in Python 2.7 and not in Python 3 is because in Python 2 it returned a list and in Python 3 it returns a dictionary view .

To get the same behavior, you have to wrap it in list() or tuple() .

The most memory efficient way would be to create a tuple of the keys.

keys = tuple(my_dict.keys())
my_dict[keys[0]]

However, whenever you change the dictionary, you'd have to update/recreate keys .

Another thing to note is order is not guaranteed before Python 3.7, though once keys is created, it's order is.