As a Built-in data type in Python, a dictionary entails key-value pairs. The dictionary, as a whole, is mutable though its keys are immutable and unique. Even though the language doesn’t offer a built-in add feature, you can manually add items to the Python dictionary in multiple ways.
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In this article, we’ll explore some ways to add items to the Python dictionary, including the assignment operator, merge operator, and update operator, besides the commonly used update method.
The simplest way to add Python dictionary items is by using = or the assignment operator. The method designates a new value to the key or overwrites the current value. The below example exhibits the assignment operator in action:
dict_example = {'a': 1, 'b': 2} print("original dictionary: ", dict_example) dict_example['a'] = 100 # existing key, overwrite dict_example['c'] = 3 # new key, add dict_example['d'] = 4 # new key, add print("updated dictionary: ", dict_example) Outputoriginal dictionary: {'a': 1, 'b': 2}updated dictionary: {'a': 100, 'b': 2, 'c': 3, 'd': 4}
In addition, there is also a way to stop the assignment operator from overwriting the key values. The trick is to add an ‘if’ condition to the syntax.
dict_example = {'a': 1, 'b': 2} print("original dictionary: ", dict_example) dict_example['a'] = 100 # existing key, overwrite dict_example['c'] = 3 # new key, add dict_example['d'] = 4 # new key, add print("updated dictionary: ", dict_example) # add the following if statements if 'c' not in dict_example.keys(): dict_example['c'] = 300 if 'e' not in dict_example.keys(): dict_example['e'] = 5 print("conditionally updated dictionary: ", dict_example)
Output original dictionary: {'a': 1, 'b': 2} updated dictionary: {'a': 100, 'b': 2, 'c': 3, 'd': 4} conditionally updated dictionary: {'a': 100, 'b': 2, 'c': 3, 'd': 4, 'e': 5}
In the example above, the value of ‘c’ remained the same even after the new value definition due to the use of the ‘if’ conditional operator.
Another way to append a Python dictionary or update the current key-value pair is through the update() method. This technique lets you rewrite/overwrite key values with newer ones. The below example illustrates how to use the update() to re-create your Python dictionary.
site = {'Website':'Xperti', 'Tutorial':'How To Add Python Dictionary Items'} print("original dictionary: ", site) # update the dictionary with the author key-value pair site.update({'Author':'Jordon Brown'}) print("updated with Author: ", site) # create a new dictionary guests = {'Guest1':'Rick Brown', 'Guest2':'Jim Brown'} # update the original dictionary with the new dictionary site.update(guests) print("updated with new dictionary: ", site
Output
original dictionary: {'Website': 'Xperti', 'Tutorial': 'How To Add Python Dictionary Items'} updated with Author: {'Website': 'Xperti', 'Tutorial': 'How To Add Python Dictionary Items', 'Author': 'Jordon Brown'} updated with new dictionary: {'Website': 'Xperti', 'Tutorial': 'How To Add Python Dictionary Items', 'Author': 'Jordon Brown', 'Guest1': 'Rick Brown', 'Guest2': 'Jim Brown'}
You can also merge two existing Python dictionaries and create a new one using Merge | operator. The example below illustrates how you can use this to create new dictionaries with ease.
site = {'Website':'Xperti', 'Tutorial':'How To Add Python Dictionary Items', 'Author':'Jordon'} guests = {'Guest1':'Rick Brown', 'Guest2':'Jim Brown'} new_site = site | guests print("site: ", site) print("guests: ", guests) print("new_site: ", new_site)
site: {'Website': 'Xperti', 'Tutorial': 'How To Add Python Dictionary Items', 'Author': 'Jordon'} guests: {'Guest1': 'Rick Brown', 'Guest2': 'Jim Brown'} new_site: {'Website': 'Xperti', 'Tutorial': 'How To Add Python Dictionary Items', 'Author': 'Jordon', 'Guest1': 'Rick Brown', 'Guest2': 'Jim Brown'}
In addition to the methods above, you can also update Python dictionary items through the update |= operator. The below example illustrates how to update values in two dictionaries and create a new updated one.
site = {'Website':'Xperti', 'Tutorial':'How To Add Python Dictionary Items', 'Author':'Jordon'} guests = {'Guest1':'Rick Brown', 'Guest2':'Jim Brown'} site |= guests print("site: ", site)
site: {'Website': 'Xperti', 'Tutorial': 'How To Add Python Dictionary Items', 'Author': 'Jordon', 'Guest1': 'Rick Brown', 'Guest2': 'Jim Brown'}
Unlike tuples and lists, there is no definite way to add, append, or insert an item in a Python dictionary. So, the trick is to define a new index value to replace the pre-existing one to add or replace Python dictionary items at will.
In this article, we explored multiple ways to use Python’s add-to-dictionary feature with examples. Choose the one that you find the easiest and create better Python dictionaries.
Also Read: How To Use Python Dataclassses?
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