Is it possible to add a pair of <key, value> to the end of a dictionary in python

Question

When I introduce a new pair, it is inserted at the beginning of the dictionary. Can I add it at the end?

Answer 1

UPDATE

Starting with Python 3.7, dictionaries remember the insertion order . By simply adding a new value, you can be sure that it will be “at the end” if you iterate over the dictionary.

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Dictionaries have no order and, therefore, have no beginning or end. The display order is arbitrary. If you need order, you can use list tuple instead of dict :

 In [1]: mylist = [] In [2]: mylist.append(('key', 'value')) In [3]: mylist.insert(0, ('foo', 'bar')) 

You can easily convert it to a dict later:

 In [4]: dict(mylist) Out[4]: {'foo': 'bar', 'key': 'value'} 

Alternatively, use collections.OrderedDict as suggested by IamAlexAlright.

Answer 2

Not. Check out the OrderedDict module from the collection.

Answer 3

A dict in Python is not "ordered" - in Python 2.7+ there are collections.OrderedDict , but apart from that - no ... The key point of the dictionary in Python is the effective value of key-> lookup .. The order in which you see them is completely arbitrary depending on the hashing algorithm ...