How to Slice a Dictionary in Python

With Python, we can easily slice a dictionary to get just the key/value pairs we want. To slice a dictionary, you can use dictionary comprehension.

dictionary = {"apples":3, "bananas":4, "pears":5, "lemons":10, "tomatoes": 7}

keys_for_slicing = ["apples","lemons"]

sliced_dict = {key: dictionary[key] for key in keys_for_slicing }

print(sliced_dict)

#Output:
{'apples': 3, 'lemons': 10}

In Python, dictionaries are a collection of key/value pairs separated by commas. When working with dictionaries, it can be useful to be able to easily access certain elements.

To slice a dictionary given a list of keys, we can use dictionary comprehension to loop over each item and return the items which have keys in our list.

Below is a simple example in Python of how to slice a dictionary given a list of keys.

dictionary = {"apples":3, "bananas":4, "pears":5, "lemons":10, "tomatoes": 7}

keys_for_slicing = ["apples","lemons"]

sliced_dict = {key: dictionary[key] for key in keys_for_slicing }

print(sliced_dict)

#Output:
{'apples': 3, 'lemons': 10}

Slicing the First N Items of a Dictionary with islice() Function in Python

If you want to slice the first n key/value pairs from a dictionary, we can use a different method from above.

The itertools module has many great functions which allow us to iterate over collections and perform complex tasks easily.

One function which is useful is the itertools islice() function. We can slice items out of a dictionary with islice()

For example, to slice the first two items out of a dictionary, we pass dict.items() and 2 to islice()

Below is an example of how to get the first n items of a dictionary in Python.

import itertools

dictionary = {"apples":3, "bananas":4, "pears":5, "lemons":10, "tomatoes": 7}

first_two_items = dict(itertools.islice(dictionary.items(),2))

print(first_two_items)

#Output:
{'apples': 3, 'bananas': 4}

Hopefully this article has been useful for you to learn how to slice dictionaries in your Python programs.