How to get single value from dict with single entry?

Question

I saw How to extract dictionary single key-value pair in variables suggesting:

d = {"a":1} (k, v), = d.items() 

But: I only care about the value. And I want to pass that value to a method; like:

foo(v) 

So the question is: is there a simple command that works for both python2 and python3 that gives me that value directly, without the detour of the "tuple" assignment?

Or is there a way to make the tuple assignment work for my usecase of calling a method?

Answer 1

list(d.values())[0] will be evaluated to 1. As pointed out in the comments, the cast to list is only needed in python3.

next(iter(d.values())) is another possibility (probably more memory efficient, as you do not need to create a list)

Both solution testes locally with python 3.6.0 and in TIO with python 2.

Answer 2

next(iter(d.values())) is the natural way to extract the only value from a dictionary. Conversion to list just to extract the only element is not necessary.

It is also performs best of the available options (tested on Python 3.6):

d = [{'a': i} for i in range(100000)]  %timeit [next(iter(i.values())) for i in d]  # 50.1 ms per loop %timeit [list(i.values())[0] for i in d]     # 54.8 ms per loop %timeit [list(i.values()).pop() for i in d]  # 81.8 ms per loop