Join dictionary item, keys [duplicate]

Question

Please see below code snippet for join method (used Python 2.7.2):

iDict={'1_key':'abcd','2_key':'ABCD','3_key':'bcde','4_key':'BCDE'}
'--'.join(iDict)

Result shown as

'2_key--1_key--4_key--3_key'

Please comment why only keys are joined? Also the sequence is not in order.

Note - below are the individual methods.

• '--'.join(iDict.values()) ==> 'ABCD--abcd--BCDE--bcde' ==> the sequence is not in order
• '--'.join(iDict.keys()) ==> '2_key--1_key--4_key--3_key' ==> the sequence is not in orde

Answer 1

If you see the docs, you learn that iterating over dict returns keys.

You need to iterate over dict.items(), that it over tuples (key, value):

'--'.join(iDict.items())

If you need to have key AND value joined in one string, you need to explicitly tell Python how to do this:

'--'.join('{} : {}'.format(key, value) for key, value in iDict.items())

Answer 2

Python dictionaries are unordered (or rather, their order is arbitrary), and when you iterate on them, only the keys are returned:

>>> d = {'0':0, '1':1, '2':2, '3':3, '4':4}
>>> print(d)
{'4': 4, '1': 1, '0': 0, '3': 3, '2': 2}

If you need both keys and values, use iDict.items().

If you need ordering, use collections.OrderedDict.