How To Sort A Dictionary By Values In Python?

Sort a dictionary by values! How can we sort elements inside dictionaries using their values in Python? That is a good question while considering Dictionary in Python.

This article will discuss the various ways to sort elements kept inside dictionaries by values. However, before we proceed further, let’s discuss what a dictionary in Python is and what it means to sort a dictionary by value.

Dictionary in Python

Dictionary in Python is an important data structure. By using Dictionary, we can store data in the form of key-value pairs. Each key in a dictionary can store at most one value. While declaring a key it must be noted that the keys in the dictionary must be immutable in nature and the supported data types of declaring a key are: integers, strings, and tuples as these are immutable. Also, the dictionary has a unique property that doesn’t allow duplication of keys inside the dictionary.

Note: The older versions of Python beyond 3.7, had dictionaries with unordered data structures. But since Python 3.7 came into existence, dictionaries are ordered data structures. This implies that the elements inside the dictionaries are now stored in an ordered manner.

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Creating a dictionary

You can create a dictionary in Python by enclosing key-value pairs inside curly braces ({}). Each key-value pair is separated with another key-value pair with the help of commas (,).

Syntax:

{key1 : value1, key2 : value2, key3 : value3, key4 : value4,…..}

 Let’s have a look at the below-given code snippet which describes the creation of a dictionary in Python.

So, do not use mutable objects as keys inside the dictionary. Instead, we can convert a list into a tuple (immutable type) and then make it a key.

Before finding out how to sort a dictionary by values, let’s have a look at a few additional functions :

items() method of a dictionary

The items() method of a dictionary is used to return a view object that displays a list of tuples containing the key-value pair of the corresponding tuple. Let’s implement a code to understand the working of this method.

Output:

The functions that are declared without a name are called anonymous functions. These anonymous functions are defined using a lambda keyword. That’s the reason why the anonymous functions are also called lambda functions.

Syntax of lambda functions is given as:

lambda arguments: expression

A lambda function can have any number of arguments. However, it has only one expression. It is evaluated and returned after the function operation. Let’s see a sample program to observe the working of the lambda functions.

Output

The sorted function is used to sort an iterable object in a particular order. And then it returns the result in form of a list.

Syntax

sorted(iterable, key, reverse)

The function accepts three parameters that are discussed in detail below:

• iterable: It is an object that can be iterated. Such as a sequence type (like list, tuple, string) or a collection type (like a dictionary, set, frozen set, etc.) or it could be any other iterable object.
• key: It is an optional parameter inside the function. It accepts a function to be passed inside it This becomes the basis over which element in the iterable is compared for sorting. The default value is set to None.
• reverse: It is also an optional parameter and accepts Boolean values in True and False. If the value passed is True, then the sorted list will be displayed in reverse order. Otherwise, the default value is set to False, which displays the result in ascending order.

Let’s have a look at an example of using the sorted() function

The output of sorted() to sort a dictionary by values:

Now that we have an understanding of what keys and values are inside a dictionary. Also, few additional functions such as items(), lambda functions, and sorted() function. Finally, we shall put our focus towards our main goal i.e., sorting the dictionary by its values.

To understand it in a better way, let’s formulate it in a problem statement. Recall in the earlier section, we created a dictionary representing the Test cricket rankings of different countries where the team name was the key and its ranking was the value that key holds. Our objective is to sort the team names based upon rankings (i.e., value) in ascending order. 

It should be noted that there aren’t any straightforward built-in functions that we can use for sorting the dictionary by values. Therefore, to achieve our objective we will make use of those additional Python functions that we studied earlier in the tutorial.

Thus, to sort a dictionary by values, we can verify our result by printing the ‘sorted_ranking’ variable our original dictionary will get sorted by the values. While saving and executing the above code, the output will look like this:

Test your understanding of different Python concepts

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