CODEWITHSUNDEEP
pythondictionary
locoboy
locoboy

Reputation: 38940

Pick a key from a dictionary python

go through a dictionary picking keys from it in a loop?

For example lets say I have the following dictionary: {'hello':'world', 'hi':'there'}. Is there a way to for loop through the dictionary and print hello, hi?

on a similar note is there a way to say myDictionary.key[1] and that will return hi?

Upvotes: 1

Views: 19724

Answers (5)

Donald Miner
Donald Miner

Reputation: 39893

You can use the .keys() method:

for key in myDictionary.keys():
   print(key)

You can also use .items() to iterate through both at the same time:

for key, value in myDictionary.items():
   print(key, value)

Upvotes: 5

user688635
user688635

Reputation:

Using the dictionary name as a sequence produces all the keys:

>>> d={'hello':'world', 'hi':'there'}
>>> list(d)
['hi', 'hello']

so list({'hello':'world', 'hi':'there'})[1] produces element 1 of the list of keys.

This is of limited use, however, because dictionaries are unordered. And their order may be different than the order of insertion:

>>> d={'a': 'ahh', 'b': 'baa', 'c': 'coconut'}
>>> d
{'a': 'ahh', 'c': 'coconut', 'b': 'baa'}

You can do sorted(list({'hello':'world', 'hi':'there'}))[1] for the 1 element of a sorted list of the keys of your dict. That produces 'hi' in this case. Not the most readable or efficient though...

You should look at OrderedDict if you want a sorted order.

Or just sort into a list:

>>> d={'a': 'ahh', 'b': 'baa', 'c': 'coconut'}
>>> l=[(k,v) for k, v in d.items()]
>>> l.sort()
>>> l[1]
('b', 'baa')
>>> l[1][0]
'b'

You can reverse (k,v) to (v,k) if you want to sort by value instead of by key.

Upvotes: 2

Raymond Hettinger
Raymond Hettinger

Reputation: 226306

Sounds like a list of keys would meet your needs:

>>> d = { 'hello': 'world', 'hi': 'there' }
>>> keys = list(d)
>>> keys
['hi', 'hello']
>>> from random import choice
>>> choice(keys)
'hi'

Upvotes: 0

Mark Byers
Mark Byers

Reputation: 838196

You can iterate over the keys of a dict with a for loop:

>>> for key in yourdict:
>>>    print(key)
hi
hello

If you want them as a comma separated string you can use ', '.join.

>>> print(', '.join(yourdict))
hi, hello

on a similar note is there a way to say myDictionary.key1 and that will return hi

No. The keys in a dictionary are not in any particular order. The order that you see when you iterate over them may not be the same as the order you inserted them into the dictionary, and also the order could in theory change when you add or remove items.

if you need an ordered collection you might want to consider using another type such as a list, or an OrderedDict

Upvotes: 4

Cat Plus Plus
Cat Plus Plus

Reputation: 129764

dict.iterkeys in Python 2, dict.keys in Python 3.

d = { 'hello': 'world', 'hi': 'there' }
for key in d.iterkeys():
    print key

Upvotes: 1

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