Convert a list of dictionaries to an unordered list of just values?

Question

How can I quickly convert a list of dictionaries to a simple list of just the values if the order is not important?

For example:

results = [{'id':'abcd'},
           {'id':'bcde'},
           {'id':'cdef'}]

to simply

results = ('abcd','bcde','cdef')

Probably need to reword your question. That's not a dictionary of key-value pairs. Its a list of dictionaries. — Hoopdady, Jul 08 '14 at 12:41

score 3 · Answer 1 · answered Jul 08 '14 at 12:38

You can try this:

>>> results = [{'id':'abcd'},
...            {'id':'bcde'},
...            {'id':'cdef'}]
>>>
>>> tuple(d['id'] for d in results)
('abcd', 'bcde', 'cdef')

Note that this is not a list but rather a tuple. If you want a list instead:

>>> [d['id'] for d in results]
['abcd', 'bcde', 'cdef']

Eli · Answer 2 · 2014-07-08T12:44:59.950

1

This should do it:

>>> [val for dic in results for val in dic.values()]

['abcd', 'bcde', 'cdef']

If you want a tuple, just enclose in tuple with parens instead:

>>> tuple(val for dic in results for val in dic.values())

('abcd', 'bcde', 'cdef')

Both of the above work even if dictionaries have more than one value, and regardless of what the keys in the dictionaries are.

edited Jul 08 '14 at 12:44

answered Jul 08 '14 at 12:41

Eli

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Is the list created by `dic.values()` needed? – usual me Jul 08 '14 at 12:46
Idea is to make things work regardless of keys. It's all in a list comprehension, so Python interpreter can figure out the fastest way of doing it. – Eli Jul 08 '14 at 12:48

Don · Answer 3 · 2014-07-08T12:53:13.933

This will fit your sample data:

import operator
map(operator.itemgetter('id'), results)

e.g.

results = [{'id':'abcd'},
       {'id':'bcde'},
       {'id':'cdef'}]

import operator
print map(operator.itemgetter('id'), results)

>>> ['abcd', 'bcde', 'cdef']

BUT, in a general way, you can chain the values of each dictionary in list:

import itertools
print list(itertools.chain(*map(dict.values, results)))

>>> ['abcd', 'bcde', 'cdef']

score 0 · Answer 4 · answered Jul 08 '14 at 13:53

It sounds like what you essentially want to do is concatenate the values of all the dictionaries into one list. The built-inreduce()function makes translating that into code relatively easy:

reduce(lambda a, b: a+b, (d.values() for d in results))

will give:

['abcd', 'bcde', 'cdef']

You can add an outer call totuple(), if that's what you really want to get:

('abcd', 'bcde', 'cdef')

Convert a list of dictionaries to an unordered list of just values?

4 Answers4