Python Articles - Page 958 of 1048

You can access a dictionary value to a variable in Python using the access operator []. examplemy_dict = {    'foo': 42,'bar': 12.5 } new_var = my_dict['foo'] print(new_var)OutputThis will give the output −42You can also access the value using the get method on the dictionary. examplemy_dict = {    'foo': 42,'bar': 12.5 } new_var = my_dict.get('foo') print(new_var)OutputThis will give the output −42

Python dictionaries are very difficult to handle data. They use a special system called hashing, which allows quick access to information. This specifies the cost of different operations: Time Complexities of Dictionary Operations Python dictionaries are usually fast because they use hashing to find and store data. The time complexity of dictionary operations in Python depends on the size of the dictionary and the operations performed. Here are some of the common dictionary operations - ... Read More

Very use case specific: https://stackoverflow.com/questions/30447708/split-python-dictionary-into-multiple-keys-dividing-the-values-equally

The dictionary consists of a number of buckets. Each of these buckets containsthe hash code of the object currently stored (that is not predictable from the position of the bucket due to the collision resolution strategy used)a pointer to the key objecta pointer to the value objectThis sums up to at least 12 bytes on a 32bit machine and 24 bytes on a 64bit machine. The dictionary starts with 8 empty buckets. This is then resized by doubling the number of entries whenever its capacity is reached.

There are some cases where you can simply avoid using dictionaries in Python. For example, if you're creating a dict of continuous integers to some values, consider using a list instead.If you're creating string-based keys, you might be better off using a Trie data structure(https://en.m.wikipedia.org/wiki/Trie).There are other cases where you can replace the use of dicts by some other less memory intensive data structure.But you need to understand that at some places, you have to use a dict as it helps in optimization. The python dict is a relatively straightforward implementation of a hash table. This is how hash tables ... Read More

There will never be redundant combinations in a Python dictionary because it is a hashmap. This means that each key will have exactly one associated value with it. This value can be a list or another dict though. So if you try to add a duplicate key likeExamplea = {'foo': 42, 'bar': 55} a['foo'] = 100 print(a)OutputThis will give the output{'foo': 100, 'bar': 55}If you really want multiple values for a single key, then you should probably use a list to be associated with the key and add values to that list.

One of the common approach to convert JSON data into a python tuple is converting the json data to a dict using json.loads() and then conveting it to a python tuple using dict.items(). There are several other ways or methods to convert JSON data into tuple, depending on our needs and some of them are follows below. Using json.loads() and dict.items() method Using json.loads with a Manual Tuple Construction ... Read More

You can parse JSON files using the json module in Python. This module parses the json and puts it in a dict. You can then get the values from this like a normal dict. For example, if you have a json with the following content{    "id": "file",    "value": "File",    "popup": {       "menuitem": [          {"value": "New", "onclick": "CreateNewDoc()"},          {"value": "Open", "onclick": "OpenDoc()"},          {"value": "Close", "onclick": "CloseDoc()"}       ]    } }You can load it in your python program and loop over ... Read More

If you have the exact key you want to find, then you can simply use the [] operator or get the function to get the value associated with this key. For example,Examplea = {    'foo': 45,    'bar': 22 } print(a['foo']) print(a.get('foo'))OutputThis will give the output:45 45ExampleIf you have a substring that you want to search in the dict, you can use substring search on the keys list and if you find it, use the value. For example,a = {    'foo': 45,    'bar': 22 } for key in a.keys():    if key.find('oo') > -1:       print(a[key])OutputThis will give the output45

dicts in python are heavily optimized. Creating a dict from N keys or key/value pairs is O(N), fetching is O(1), putting is amortized O(1), and so forth. You don't need to optimize them explicitly. You can be sure of this as python under the hood implements its own classes using dicts.Don't compare lists/tuples to dicts/sets though as they solve different problems.