Access an arbitrary element in a dictionary in Python

get first element of dictionary python 3
python dictionary of dictionaries
print specific key in dictionary python
python 3 dictionary
python print dictionary
python get first key, value in dict
python dictionary methods
python dictionary values

If a mydict is not empty, I access an arbitrary element as:

mydict[mydict.keys()[0]]

Is there any better way to do this?

On Python 3, non-destructively and iteratively:

next(iter(mydict.values()))

On Python 2, non-destructively and iteratively:

mydict.itervalues().next()

If you want it to work in both Python 2 and 3, you can use the six package:

six.next(six.itervalues(mydict))

though at this point it is quite cryptic and I'd rather prefer your code.

If you want to remove any item, do:

key, value = mydict.popitem()

Note that "first" is not an appropriate term here. This is "any" item, because dict is not an ordered type.

Access an arbitrary element in a dictionary in Python?, If you only need to access one element (being the first by chance, since dicts do not knows how to get the corresponding value, given a key, from a python dict. Python | Accessing Key-value in Dictionary. Dictionary is quite a useful data structure in programming that is usually used to hash a particular key with value, so that they can be retrieved efficiently. Let’s discuss various ways of accessing all the keys along with their values in Python Dictionary.

If you only need to access one element (being the first by chance, since dicts do not guarantee ordering) you can simply do this in Python 2:

my_dict.keys()[0]     -> key of "first" element
my_dict.values()[0]   -> value of "first" element
my_dict.items()[0]    -> (key, value) tuple of "first" element

Please note that (at best of my knowledge) Python does not guarantee that 2 successive calls to any of these methods will return list with the same ordering. This is not supported with Python3.

in Python 3:

list(my_dict.keys())[0]     -> key of "first" element
list(my_dict.values())[0]   -> value of "first" element
list(my_dict.items())[0]    -> (key, value) tuple of "first" element

Dictionaries in Python – Real Python, Dictionaries differ from lists primarily in how elements are accessed: List elements Almost any type of value can be used as a dictionary key in Python. You just  Note: This question is about accessing dict elements by index, which makes no sense because dicts are unordered. For a question about accessing elements in a nested dict, see Python - accessing values nested within dictionaries. – Aran-Fey Oct 9 '18 at 12:03. @Aran-Fey: unordered things have an intrinsic order. Unordered != no order

In python3, The way :

dict.keys() 

return a value in type : dict_keys(), we'll got an error when got 1st member of keys of dict by this way:

dict.keys()[0]
TypeError: 'dict_keys' object does not support indexing

Finally, I convert dict.keys() to list @1st, and got 1st member by list splice method:

list(dict.keys())[0]

Python - Dictionary, The values of a dictionary can be of any type, but the keys must be of an To access dictionary elements, you can use the familiar square brackets along with  To loop or iterate over each element of a dictionary variable, you have to use the for loop of Python. You can get the dictionary variable keys and values in the output. Use the for loop of the Python and use only keys or values in your programming.

to get a key
next(iter(mydict))
to get a value
next(iter(mydict.values()))
to get both
next(iter(mydict.items())) # or next(iter(mydict.viewitems())) in python 2

The first two are Python 2 and 3. The last two are lazy in Python 3, but not in Python 2.

Python, In this, we just convert the entire dictionaries' keys extracted by keys() into a list and just access the first key. filter_none. edit close. play_arrow. link brightness_4 Since the dict doesn't preserve order, by using popitem you get items in an arbitrary (but not strictly random) order from it. Also keep in mind that popitem removes the key-value pair from dictionary, as stated in the docs. popitem () is useful to destructively iterate over a dictionary. improve this answer. edited May 23 '17 at 12:26.

As others mentioned, there is no "first item", since dictionaries have no guaranteed order (they're implemented as hash tables). If you want, for example, the value corresponding to the smallest key, thedict[min(thedict)] will do that. If you care about the order in which the keys were inserted, i.e., by "first" you mean "inserted earliest", then in Python 3.1 you can use collections.OrderedDict, which is also in the forthcoming Python 2.7; for older versions of Python, download, install, and use the ordered dict backport (2.4 and later) which you can find here.

Python 3.7 Now dicts are insertion ordered.

Python Dictionary Tutorial, The removal of an element from a dictionary can be done in several ways, Unsubscribe at any time. The reason is that we are trying to access a dictionary which doesn't exist since it has been deleted. Python dictionary is an unordered collection of items. While other compound data types have only value as an element, a dictionary has a key and a value pair. Dictionaries are optimized to retrieve values when the key is known.

20. Dictionaries, They map keys, which can be any immutable type, to values, which can be any type Python uses complex algorithms, designed for very fast access, to determine a key, we would have to iterate over every tuple, checking the 0th element. Keys are unique within a dictionary while values may not be. The values of a dictionary can be of any type, but the keys must be of an immutable data type such as strings, numbers, or tuples. Accessing Values in Dictionary. To access dictionary elements, you can use the familiar square brackets along with the key to obtain its value.

Python Dictionaries with Python, This guide discusses using Python's Dictionary object. in an array, except that array indices are numeric and keys are arbitrary strings. Python 3 - Dictionary. Each key is separated from its value by a colon (:), the items are separated by commas, and the whole thing is enclosed in curly braces. An empty dictionary without any items is written with just two curly braces, like this: {}. Keys are unique within a dictionary while values may not be.

15 things you should know about Dictionaries in Python, A dictionary is an unordered and mutable Python container that stores This function takes an arbitrary number of keywords arguments (arguments To access elements in a nested dictionary, we specify the keys using  How to Iterate Through a Dictionary in Python: The Basics. Dictionaries are an useful and widely used data structure in Python. As a Python coder, you’ll often be in situations where you’ll need to iterate through a dictionary in Python, while you perform some actions on its key-value pairs.

Comments
  • What he said.. this is only really a valid question if there's only one element in the dict, or you don't care which you get back.
  • Yup, I just need to access to whatever element in the dict, so that's why I want to access to first element.
  • @Stan: but as Greg said, there is no definite "first" element in dict. so maybe you should change your question, just to be clear
  • I think it is a valid question. If you need to access an arbitrary element, and you are sure that the dict is not empty, it may be a good idea to ask for the "first", because the number of items may not be known.
  • @MichaelScheper You have to cast to list : list(mydict.keys())[0].
  • Don't you mean dict.iterkeys().next()?
  • @John Machin: Well, the question seems to access value associated with the first key, so that's what I do in the answer as well.
  • this looks better: dict.values().__iter__().__next__() :)
  • it's annoying that dict.keys() is not directly iterable.
  • for a non-destructive popitem you can make a (shallow) copy: key, value = dict(d).popitem()
  • That only works in Python 2.x, for 3.x you have to use list(my_dict.keys())[0]
  • So, what complexity class is this? Surely, list(my_dict.keys())[0] is not lazy?
  • To clarify, what @alldayremix meant with that comment is in python 3.x my_dict.function() results do not support indexing, this is why first of all we must convert it into a list and then we can use the index [0]
  • This is the easiest solution and works in both python2 and python3.