Found 10413 Articles for Python

How to optimize Python dictionary memory usage?

Samual Sam
Updated on 30-Jul-2019 22:30:22

677 Views

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

How to check for redundant combinations in a Python dictionary?

Chandu yadav
Updated on 05-Mar-2020 07:09:45

144 Views

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.

How to convert JSON data into a Python tuple?

SaiKrishna Tavva
Updated on 14-Oct-2024 14:13:00

5K+ Views

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

How to create Python dictionary from JSON input?

George John
Updated on 17-Jun-2020 11:22:57

1K+ Views

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

How to search Python dictionary for matching key?

Ankith Reddy
Updated on 17-Jun-2020 11:17:59

4K+ Views

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

How to optimize Python Dictionary for performance?

Samual Sam
Updated on 30-Jul-2019 22:30:22

743 Views

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.

How to Pretty print Python dictionary from command line?

Arjun Thakur
Updated on 17-Jun-2020 11:14:32

1K+ Views

You can pretty print a dict in python using the pprint library. The pprint module provides a capability to “pretty-print” arbitrary Python data structures in a form which can be used as input to the interpreter. You can use it as followsExamplea = {    'bar': 22,    'foo': 45 } pprint.pprint(a, width=10)OutputThis will give the output:{'bar': 22, 'foo': 45}As you can see that even this can be unreadable. You can use the json module to actually print it better. For example,Exampleimport json a = {    'bar': 22,    'foo': 45 } print(json.dumps(a, indent=4))OutputThis will give the output:{    "bar": 22,    "foo": 45 }

How to truncate Key Length in Python Dictionary?

Chandu yadav
Updated on 05-Mar-2020 07:00:13

627 Views

You can use a list comprehension to truncate keys in a python dict. Iterate over the keys in the dict, and create a new dict with the truncated keys. exampledef truncate_keys(a, length):    return dict((k[:length], v) for k, v in a.items()) a = {'foo': 125, 'bar': 'hello'} b = truncate_keys(a, 2) print(b)OutputThis will give the output{'fo': 125, 'ba': 'hello'}You need to vary about the name collision though. This is because if 2 strings have the same prefix, they will override the values.

How to create Python dictionary from the value of another dictionary?

Samual Sam
Updated on 17-Jun-2020 11:11:54

2K+ Views

You can do this by merging the other dictionary to the first dictionary. In Python 3.5+, you can use the ** operator to unpack a dictionary and combine multiple dictionaries using the following syntax −Syntaxa = {'foo': 125} b = {'bar': "hello"} c = {**a, **b} print(c)OutputThis will give the output −{'foo': 125, 'bar': 'hello'}This is not supported in older versions. You can however replace it using the following similar syntax −Syntaxa = {'foo': 125} b = {'bar': "hello"} c = dict(a, **b) print(c)OutputThis will give the output −{'foo': 125, 'bar': 'hello'}Another thing you can do is using copy and ... Read More

How do Python Dictionary Searching works?

Lakshmi Srinivas
Updated on 30-Jul-2019 22:30:22

712 Views

Dicts are hash tables. No tree searching is used. Looking up a key is a nearly constant time(Amortized constant) operation, regardless of the size of the dict. It creates the hash of the key, then proceeds to find the location associated with the hashed value. If a collision listed address is encountered, it starts the collision resolution algorithm to find the actual value.This causes dictionaries to take up more space as they are sparse.

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