Python: Retrieve items from a set

Question

In general, Python sets don\'t seem to be designed for retrieving items by key. That\'s obviously what dictionaries are for. But is there anyway that, given a key, you can

Answer 1

Yes, you can do this: A set can be iterated over. But note that this is an O(n) operation as opposed to the O(1) operation of the dict.

So, you have to trade off speed versus memory. This is a classic. I personally would optimize for here (i.e. use the dictionary), since memory won't get short so quickly with only 10,000,000 objects and using dictionaries is really easy.

As for additional memory consumption for the firstname string: Since strings are immutable in Python, assigning the firstname attribute as a key will not create a new string, but just copy the reference.