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Discover how to create a multidimensional array in Matlab with a size defined by two vectors, both in 2D and 3D spaces.
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How to Efficiently Allocate an Array in Matlab Using Two Vectors

In the world of programming, specifically when working with Matlab, one may often need to allocate space for arrays based on specified dimensions. This can be particularly challenging when these dimensions are defined by multiple vectors, especially when shifting between two-dimensional (2D) and three-dimensional (3D) spaces. In this post, we'll tackle the question: How do you allocate an array with a size defined by two vectors?

Understanding the Problem

You may find yourself in a situation where you need to create a zeros array in Matlab. This array's dimensions depend on a rectangular domain defined by two corner points, for example, a left-bottom corner and a right-top corner. The goal is to set parameters that allow for flexibility in dimensions, adapting quickly from 2D to 3D.

Example Scenario

Consider you have the following two vectors representing the corners of your domain:

2D Example:

Left-Bottom Corner: [-1, -2]

Right-Top Corner: [2, 2]

3D Example:

Left-Bottom Corner: [-2, -2, -2]

Right-Top Corner: [2, 2, 2]

For both scenarios, you want to create an array filled with zeros that match these dimensions.

Solution Breakdown

Step 1: Define Your Corners and Domain Size

First, you will need to define your corner points and calculate the size of your domain:

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

Now do the same for 3D:

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

Step 2: Set Number of Pixels

Define how many pixels you want in each dimension. This is crucial as it will dictate the size of the array you are about to create.

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

Step 3: Create Array of Zeros

Instead of using conditional statements to check whether you're in 2D or 3D, you can use Matlab's functionality to create the array easily.

This is where the magic happens. You can simply concatenate nb_pixels and dim as follows:

For 2D:

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

For 3D:

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

Simplified Approach

You can eliminate the need for the if statement entirely and create a more elegant and dynamic solution. This allows Matlab to handle both cases seamlessly:

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

Conclusion

By using the zeros function in conjunction with concatenated vectors, you can easily create arrays of varying dimensions without cumbersome conditional checks. This simple yet powerful approach not only improves readability but also enhances the efficiency of your Matlab code. Whether you are working in 2D or 3D, using this method can streamline your coding process and reduce errors.

Next time you need to allocate an array based on vector-defined dimensions, remember to harness the flexibility that Matlab offers! Happy coding!