How to convert a dictionary into a flat list?

Question

Given a Python dict like:

{
  'a': 1,
  'b': 2,
  'c': 3
}

What's an easy way to create a flat list with keys and values in-line? E.g.:

['a', 1, 'b', 2, 'c', 3]

Answer 1

In [39]: d = {                                   
  'a': 1,
  'b': 2,
  'c': 3
}

In [40]: list(itertools.chain.from_iterable(d.items()))
Out[40]: ['b', 2, 'a', 1, 'c', 3]

Note that dicts are unordered, which means that the order in which you enter keys is not always the order in which they are stored. If you want to preserve order, you might be looking for an ordereddict

Answer 2

You can use sum:

>>> d = {'a': 1, 'b': 2, 'c': 3}
>>> sum(d.items(), tuple())
('a', 1, 'c', 3, 'b', 2)

Answer 3

res_list = []
for k, v in d:
    res_list.append(k).append(v)