Initializing python3 dict with kv at end

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In python3, (specifically 3.6 onwards) the dictionary keeps the ordering, which is great. However, I would like to initialize a dict with a kv pair 'at the end'. For example:

>>> data = {
    'Z': []
    # 'from': ['tos'], // adjacency list
}
>>> data['a']='b'
>>> data['b']='c'

>>> data
{'Z': [], 'a': 'b', 'b': 'c'}

Is this possible to do? What I want is as follows:

>>> data
{'a': 'b', 'b': 'c', 'Z': []} # 'Z' is the last element

I am not 100% certain if I understand what you would like to do but is it this:

from collections import OrderedDict
data = OrderedDict({
    'Z': []
})

def add_to_dict(key, value): 
    data[key] = value
    data.move_to_end('Z')

add_to_dict('a', 'b')
print(data).  # OrderedDict([('a', 'b'), ('Z', [])])

Initializing a dictionary in python with a key value and no , I only want to initialize keys but I don't know the corresponding values until I have to set them later. Basically I know what keys I want to add the� Python dictionary is an associative container that contains the items in key/value pairs. In Python, there are Different Ways to Initialize Dictionary. Initialize an empty dictionary. Define dict with initial None values. Initialize Dictionary using dict constructor. Initialize dictionary using dict() and zip() methods; Using defaultdict. Using

class CustomDict(dict):
    def move_to_end(self, key):
        value = self[key]
        del self[key]
        self[key] = value


d = CustomDict({"z": [], "hey": "world"})
d.move_to_end("z")
print(d)

Outputs:

{'hey': 'world', 'z': []}

You could also create a custom dict object to automatically place the key z unto the end, but that is a bit more work. Check out this post here for reference.

Python, Python end parameter in print() � Python | sep parameter in print() � Python | Output Formatting � Python | Set But its always wanted a method to initialize the dict. keys with list. Python3 code to demonstrate setdefault() can be used to perform this by specifying key-value pairs within a comprehension. A Computer Science portal for geeks. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview Questions.

Not sure if you're referring to reversing the data within the dict once new data is added i.e a new k,v pair but this is how you can add to a current dictionary:

class storeDict(dict):

    def __init__(self):
       self = dict()

    def add(self, key, value):
       self[key] = value

    # create instance of class storeDict
    newDict = storeDict()
    newDict.add('apples', 1)
    newDict.add('oranges', 2)

this just an example, that can be applicable to your question. Hope that helps :)

Python, Python3 code to demonstrate working of. # Initialize printing result. print ( " Dictionary after Initializing multiple key-value : " + str (res))� Python – Assigning Key values to list elements from Value list Dictionary Last Updated: 01-08-2020 Given List of elements, map them with keys of matching value from value list.

Zero to Hero Python Cheat Sheet: Working With Dictionaries and Sets, Initialization. Dictionaries are also initialized using the curly braces {} , and the key-value pairs are declared using the key:value syntax� In this step-by-step tutorial, you'll take a deep dive into how to iterate through a dictionary in Python. Dictionaries are a fundamental data structure, and you'll be able to solve a wide variety of programming problems by iterating through them.

How to initialize a dictionary with keys in Python, A dictionary is a collection of key-value pairs. Initializing a dictionary with keys adds keys to the dictionary upon its creation. For example, initializing a dictionary � Method 2: Python NumPy module to create and initialize array. Python NumPy module can be used to create arrays and manipulate the data in it efficiently. The numpy.empty() function creates an array of a specified size with a default value = ‘None’. Syntax:

Python | Initialize a dictionary with only keys from a list Last Updated: 15-02-2019 Given a List, the task is to create a dictionary with only keys by using given list as keys.

Comments
  • And what is the problem with your approach..?
  • @yatu I want Z at the end
  • could just reverse the dict then to get that order then
  • i don't understand, you want to reverse the dictionary? or you want to initiate it like that? Both are possible of course
  • regular dict does not have the .move_to_end() method of OrderedDict (yet) if that is your question
  • Me too. Alternatives seem to be discussed in stackoverflow.com/questions/16664874/…