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Explore how to effortlessly compute the `Cartesian product` of two lists containing dictionaries in Python using list comprehension!
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Exploring the Cartesian Product of Two Lists of Dictionaries in Python

Are you working with Python and need to compute the Cartesian product of two lists that consist of dictionaries? This task might seem daunting at first, but fear not! In this post, we’ll demystify this process and show you how to achieve it using simple techniques, specifically with list and dictionary comprehension. Let’s jump right in!

The Problem Statement

Imagine you have two lists of dictionaries:

[[See Video to Reveal this Text or Code Snippet]]

You want to create a new list that represents every possible combination of dictionaries from the two lists. The expected output for this operation would be:

[[See Video to Reveal this Text or Code Snippet]]

The challenge is to achieve this using only list and dictionary comprehensions, and without importing any libraries if possible.

Solution Breakdown

We’ll explore two methods to solve this problem:

Using a lambda function (one-liner, no imports)

Using the itertools.product method (a cleaner approach)

Method 1: Lambda Function

The first method utilizes a recursive lambda function to achieve the Cartesian product. Here’s how it works:

[[See Video to Reveal this Text or Code Snippet]]

How It Works:

The function f takes two arguments: a list of dictionaries (d) and a current combination (c).

If there are no dictionaries left (if not d), it returns the current combination in a list.

If there are dictionaries left, it loops through the keys in the first dictionary and calls itself recursively with the remaining dictionaries.

Output:

[[See Video to Reveal this Text or Code Snippet]]

Method 2: Using itertools.product

While the previous method is clever, it can be somewhat difficult to read. Let’s look at a more straightforward way to achieve the same result using the product method from the itertools library:

[[See Video to Reveal this Text or Code Snippet]]

How It Works:

We import the product function from the itertools library which generates the Cartesian product directly.

Using a list comprehension, we merge each pair of dictionaries from the two lists (j from a and k from b).

The {**j, **k} syntax merges the two dictionaries into one.

Output:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Computing the Cartesian product of two lists of dictionaries in Python can be achieved through different methods. Whether you prefer a recursive lambda function for its brevity or the itertools.product method for its clarity, you have the tools at your disposal! We hope this post has simplified your approach to this problem. Happy coding!