Last element in OrderedDict

Question

I have od of type OrderedDict. I want to access its most recently added (key, value) pair. od.popitem(last = True) would do it, but would

Answer 1

Your idea is fine, however the default iterator is only over the keys, so your example will only return the last key. What you actually want is:

class MyOrderedDict(OrderedDict):
    def last(self):
        return list(self.items())[-1]

This gives the (key, value) pairs, not just the keys, as you wanted.

Note that on pre-3.x versions of Python, OrderedDict.items() returns a list, so you don't need the list() call, but later versions return a dictionary view object, so you will.

Edit: As noted in the comments, the quicker operation is to do:

class MyOrderedDict(OrderedDict):
    def last(self):
        key = next(reversed(self))
        return (key, self[key])

Although I must admit I do find this uglier in the code (I never liked getting the key then doing x[key] to get the value separately, I prefer getting the (key, value) tuple) - depending on the importance of speed and your preferences, you may wish to pick the former option.