How to switch between keys and values in python dictionary in place (without changing it's location in memory)

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i was asked to write a code including a function- reverse_dict_in_place(d)

which switches between keys and values of the inputed dictionary without changing the dictionary's location in memory (in place).

however, testing it with id() function shows that all my solutions do change dictionaries memory location..

def reverse_dict_in_place(d):
    d={y:x for x,y in d.items()}
    return d

Alternative to current ones which allows values to be same as keys. Works in mostly the same way though, however once again no two values may be the same.

def reverse_dict_in_place(d):
    copy = d.copy().items()
    d.clear()
    for k, v in copy:
        d[v] = k
    return d

>>> x = {0: 1, 1: 2}
>>> y = reverse_dict_in_place(x)
>>> id(x) == id(y)
True
>>> 

Python program to Swap Keys and Values in Dictionary , Method#2 (Handles multiple same values): In this approach we will check if value is already present or not. If present then just append it to the list. 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 swapping the keys and values in Python Dictionary.


Python, Python - Keys associated with Values in Dictionary � Python | Get all tuple keys from dictionary � Python dictionary with keys having multiple inputs� Swap keys and values in a Python dictionary # python. petercour Jul 3, 2019 ・1 min read. A dictionary is a one to one mapping. Every key has a value.


Swap keys and values in a Python dictionary - DEV, Swap values. You can easily swap the key,dictionary pairs in Python, with a one liner. dict = {value:key for key� 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.


Note: @NightShade has posted a similar answer as my below answer, earlier than I posted.


You can try this:

def reverse_dict_in_place(d):
    d_copy = d.copy()
    d.clear()
    for k in d_copy:
        d[d_copy[k]] = k

This would work even if one of the dictionary's values happens to also be a key (as tested out below)

Testing it out:

my_dict = {1:1, 2:'two', 3:'three'}
reverse_dict_in_place(my_dict)
print (my_dict)

Output:

{1: 1, 'two': 2, 'three': 3}

How to update key and value in dictionary in python, Updating key and value is nothing but removing the key-value pair and adding a new one. Example : Are there any performance impacts of using Python dictionaries? Jatin Goyal, MTech from Indian Institute of Technology, Delhi ( 2017) Change the name of a key in dictionary (*In python you can not update a key. You can assign a dictionary value to a variable in Python using the access operator []. For example,Examplemy_dict = { 'foo': 42, 'bar'


Python Dictionary update(), The update() method updates the dictionary with the elements from the another dictionary object or from an iterable of key/value pairs. update() method adds element(s) to the dictionary if the key is not in the dictionary. If the key is Click on the different category headings to find out more and change our default settings. Let’s discuss various ways of accessing all the keys along with their values in Python Dictionary. Method #1 : Using in operator Most used method that can possibly get all the keys along with its value, in operator is widely used for this very purpose and highly recommended as offers a concise method to achieve this task.


How to change a value in a dictionary in Python, In this short tutorial, you will learn how to change the value associated with a key in a Duration: 0:59 Posted: May 30, 2018 In case you need a declarative solution, you can use dict.update() to change values in a dict. Either like this: my_dict.update({'key1': 'value1', 'key2': 'value2'}) or like this: my_dict.update(key1='value1', key2='value2') via dictionary unpacking. Since Python 3.5 you can also use dictionary unpacking for this:


20. Dictionaries — How to Think Like a Computer Scientist: Learning , Python uses complex algorithms, designed for very fast access, to determine The values in a dictionary are accessed with keys, not with indices, so there is no The del statement removes a key:value pair from a dictionary. Or if we're expecting more pears soon, we might just change the value associated with pears:. 7 Since keys are what dictionaries use to lookup values, you can't really change them. The closest thing you can do is to save the value associated with the old key, delete it, then add a new entry with the replacement key and the saved value. Several of the other answers illustrate different ways this can be accomplished.