3 min read•june 24, 2024
Dictionaries Python are powerful tools for organizing and data. They use , allowing quick retrieval of information based on unique identifiers. This structure is perfect for tasks like counting occurrences or representing relationships between entities.
Python's dictionary methods offer versatile ways to manipulate data. From merging dictionaries to creating them from other data structures, these methods provide flexibility. Advanced concepts like and further enhance dictionaries' efficiency and adaptability in various programming scenarios.
my_dict = {"key1": value1, "key2": value2}
or the ###[dict](https://www.fiveableKeyTerm:dict)()_0###
constructor my_dict = dict(key1=value1, key2=value2)
my_dict["new_key"] = new_value
or the [update()](https://www.fiveableKeyTerm:update())
method my_dict.update({"new_key": new_value})
[del](https://www.fiveableKeyTerm:del)
statement del my_dict["key"]
or the [pop()](https://www.fiveableKeyTerm:pop())
method value = my_dict.pop("key")
value = my_dict["key"]
or the [get()](https://www.fiveableKeyTerm:get())
method value = my_dict.get("key")
in
operator if "key" in my_dict:
or the [keys()](https://www.fiveableKeyTerm:keys())
method if "key" in my_dict.keys():
for key in my_dict:
, values for value in my_dict.[values()](https://www.fiveableKeyTerm:values()):
, or key-value pairs for key, value in my_dict.[items()](https://www.fiveableKeyTerm:items()):
()len(my_dict)
to return the number of key-value pairs, my_dict.[clear()](https://www.fiveableKeyTerm:clear())
to remove all key-value pairs, and my_dict.[copy()](https://www.fiveableKeyTerm:copy())
to return a shallow copy of the dictionaryupdate()
method dict1.update(dict2)
or the (**
) merged_dict = {**dict1, **dict2}
dict([(key1, value1), (key2, value2)])
or two parallel lists dict(zip(keys_list, values_list))
value = my_dict["key1"]["key2"]
or the get()
method value = my_dict.get("key1", [{}](https://www.fiveableKeyTerm:{})).get("key2")
my_dict["key"] += 1
or appending to list values my_dict["key"].append(new_item)
my_dict.setdefault("key", default_value)
returns the value for the key if it exists, otherwise sets the key with the default value and returns itmy_dict.[popitem()](https://www.fiveableKeyTerm:popitem())
removes and returns an arbitrary key-value pair as a tuplemy_dict.fromkeys(keys_iterable, value=None)
creates a new dictionary with keys from the iterable and optional default value[defaultdict](https://www.fiveableKeyTerm:defaultdict)
is a subclass of dict
that allows specifying a default value for missing keys and is useful for counting or grouping items without explicitly checking for key existence[OrderedDict](https://www.fiveableKeyTerm:OrderedDict)
is a subclass of dict
that remembers the order in which key-value pairs were added and is useful when the order of insertion matters (LRU caches, preserving configuration file structure)