Creating an Empty Array in MATLAB - A Comprehensive Guide with Code Samples

In this detailed article, we will explore the process of creating empty arrays within MATLAB. We’ll look at the significance of these structures, their usage, and showcase various examples to provide …

Updated November 12, 2023

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In this detailed article, we will explore the process of creating empty arrays within MATLAB. We’ll look at the significance of these structures, their usage, and showcase various examples to provide you with a better understanding of when and how to use them effectively. Additionally, we will discuss their importance in Computer Vision and the role they play in larger projects.

What is an Empty Array?

An empty array is a MATLAB data type used for organizing and managing data values within a specific structure, allowing for efficient storage, manipulation, and analysis of information. By definition, it’s a variable that stores a series of values with the same data type but does not contain any actual data until values are assigned to it. The main advantage of using empty arrays in MATLAB is their flexibility, as they can be reshaped and populated depending on your project requirements.

In MATLAB, arrays are typically of two types:

  1. Numeric Array - Stores numbers, both integers and floating-point values.
  2. Logical Array - Contains only true or false elements, useful in condition checking or filtering processes.

Creating an Empty Array in MATLAB

Creating an empty array in MATLAB is quite straightforward. The syntax for doing this involves assigning a data type to the new variable and specifying a set of parentheses enclosing the opening square bracket [ symbol, as well as the closing square bracket ]. Here’s a code snippet demonstrating how you can create an empty numeric array in MATLAB:

% Create an empty numeric array
myArray = [];

In this example, we have used myArray as the variable name for our empty numeric array. As we haven’t yet assigned any values to it, it won’t have any data associated with it at this stage.

Similarly, you can create an empty logical array by using the following syntax:

% Create an empty logical array
myArray = [];
myArray = logical([]);

In the above code snippet, we have once again utilized myArray as our variable name for our empty logical array. Additionally, we have used two methods to create the array – directly setting its data type using [] and explicitly declaring it as a logical array by assigning it through the function logical([]). Both of these techniques are equally useful within MATLAB when creating empty arrays.

Importance of Empty Arrays in Computer Vision and Other Applications

Empty arrays play a crucial role in various fields, such as Computer Vision, Artificial Intelligence, Machine Learning, and more. In the context of Computer Vision specifically, they are helpful when working with image processing tasks. Here’s how they can be beneficial:

  1. Image Segmentation - When dealing with complex images or videos, segmenting a scene into multiple regions for further analysis is often required. By using empty arrays in MATLAB, you can initialize the segmented data structures and subsequently fill them with relevant information once processed.

  2. Detection of Objects - Empty arrays can also be used to create data containers that store information about detected objects. As you iterate through image frames, these containers grow and adapt to accommodate new object detections.

  3. Data Management - Within MATLAB, empty arrays serve as versatile tools for managing large amounts of data efficiently. By dynamically resizing the array dimensions and repopulating it with updated information, you can ensure that your code remains fast, efficient, and scalable in terms of handling massive datasets or working with multidimensional data structures.

Code Samples and Examples

In this section, we will provide various code samples and tutorials to demonstrate the concepts of creating empty arrays in MATLAB. Please feel free to experiment with these examples, modify them according to your needs, and extend their functionality as required for your projects:

Example 1: Creating an Empty Array for Image Segmentation

% Initialize an empty numeric array to store segmented image regions
regionArray = [];

% Process a sequence of images, updating the regionArray with detected segments
for frameIndex = 1 : totalFrames
    % Extract regions from current image frame
    regions = segmentImage(frameIndex);

    % Append new regions to the segmented array
    regionArray = [regionArray; regions];

Example 2: Storing Detection Results in an Empty Array for Object Recognition

% Create an empty numeric array to store object detection results
detectionArray = [];

% Process a series of frames, updating the detectionArray with detected objects
for frameIndex = 1 : totalFrames
    % Run object detection algorithm on the current image frame
    detectedObjects = detectObjects(frameIndex);

    % Append new detections to the array
    detectionArray = [detectionArray; detectedObjects];

Example 3: Data Management with Empty Arrays in MATLAB

In this example, we’ll demonstrate how you can utilize empty arrays to efficiently manage a large data set. Let’s assume that we have a collection of customer records stored as an array of strings, but we need to convert them into numerical data for further analysis:

% Initialize an empty numeric array to store numerical customer data
customerData = [];

% Iterate through the list of customer records
for i = 1 : numCustomers
    % Extract relevant numerical information from each record string
    customerRecordData = extractNumericData(recordString);

    % Append the numerical data to the empty array
    customerData = [customerData; customerRecordData];


In this thorough article, we have provided a comprehensive guide on creating and utilizing empty arrays in MATLAB. We discussed their importance in various applications, such as Computer Vision and other fields where data management is critical. By understanding the basic syntax for creating both numeric and logical empty arrays, you can leverage MATLAB’s powerful capabilities to handle complex data structures efficiently and effectively.