# Solved: compute difference of all the combinations of 2 arrays

In today’s world, data manipulation and analysis are crucial for solving various problems and making decisions. Python, being one of the most widely used programming languages, offers various libraries and functions to simplify these tasks. One such problem is calculating the difference between all possible combinations of two arrays. This article will provide an in-depth understanding of how to approach this problem, its step-by-step solution, and shedding light upon the libraries and functions involved. We will also delve into related topics to understand the problem-solving process better.

In order to compute the difference for all combinations of two arrays, we will use the itertools library, specifically the product function, which helps in generating Cartesian products of input iterables. Furthermore, we will employ numpy, a popular library for scientific computing, to facilitate array operations.

## Problem Solution

We will start by importing necessary libraries, initializing two arrays, and then use itertools.product() function to determine all the possible combinations between elements of those arrays. Next, we will calculate the difference between these combinations and store the results in a list.

```import itertools
import numpy as np

array1 = np.array([1, 2, 3])
array2 = np.array([3, 4, 5])

combinations = list(itertools.product(array1, array2))
differences = [abs(combination - combination) for combination in combinations]
```

## Step-by-Step Explanation of the Code

Let’s examine each part of the code in detail to understand how it computes the differences for all combinations:

1. First, we import the required libraries – itertools and numpy:

```import itertools
import numpy as np
```

2. We create two numpy arrays with the following elements:

```array1 = np.array([1, 2, 3])
array2 = np.array([3, 4, 5])
```

3. We use the itertools.product() function to obtain all the possible combinations between elements of both arrays:

```combinations = list(itertools.product(array1, array2))
```

The output will be a list of tuples containing combinations as follows:

[(1, 3), (1, 4), (1, 5), (2, 3), (2, 4), (2, 5), (3, 3), (3, 4), (3, 5)]

4. Finally, we iterate over the combinations list and calculate the absolute difference between each pair of elements, storing the results in a list called “differences”:

```differences = [abs(combination - combination) for combination in combinations]
```

The resulting differences list will be:

[2, 3, 4, 1, 2, 3, 0, 1, 2]

## Itertools Library

• The itertools library is a powerful module in the Python Standard Library that provides a collection of fast, memory-efficient tools to work with iterators.
• It offers various functions, such as product, permutations, combinations, which can generate different types of iterator arrangements.
• These functions can help solve complex problems more efficiently and improve the performance of your code.

## Numpy Library

• Numpy is a popular open-source library for scientific computing in Python.
• It provides various tools for working with arrays, linear algebra, Fourier transform, and more.
• It enables faster numerical computations and simplifies array operations, making it a go-to choice for data manipulation and analysis tasks in Python.

By now, you should have a clear understanding of how to compute the difference of all possible combinations of two arrays using Python, specifically the itertools and numpy libraries. The modular approach of breaking down complex problems into simpler steps using specialized libraries and functions not only aids in achieving a deeper understanding of the problem but also increases code efficiency.

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