# Understanding and Implementing Double Conversion for Cells in MATLAB

In this article, we’ll take a deep dive into converting cells to doubles within the MATLAB environment. We’ll explore what double conversion is and its significance for data analysis, as well as provi …

Updated April 30, 2023

In this article, we’ll take a deep dive into converting cells to doubles within the MATLAB environment. We’ll explore what double conversion is and its significance for data analysis, as well as providing real-world examples, code snippets, and expert tips for efficient implementation in your MATLAB scripts.

## Introduction

MATLAB, developed by MathWorks, is a powerful environment for numerical computation, mathematical modeling, and algorithm development. As a programming language with numerous built-in functions and tools, it offers several data types to store and manage various kinds of information. Among these data types are cells - flexible containers capable of storing multiple elements of different types, such as numbers, strings, and even other cell arrays.

In many scenarios, we need to convert these heterogeneous contents within a cell to one specific type for efficient computational analysis or visualization purposes. One commonly used target type is `double`, which represents numerical values with floating-point precision. In this article, we will delve into the concept of cell to double conversion in MATLAB and provide practical examples of its implementation.

## Understanding Cell Arrays

Before moving forward, it’s essential to grasp the fundamentals of cells and how they differ from other data types in MATLAB. Cells are defined using curly brackets (`{ }`) and have the following syntax:

``````{element1, element2, ...}
``````

Each element inside a cell can be of any data type - including numbers, strings, arrays, other cells or even functions. Cells can store various types of information which makes them flexible containers for handling diverse data formats. This versatility also introduces some complexity when dealing with specific data conversions.

## Double Conversion in MATLAB

`double` is a numeric data type that represents real numbers, commonly used for numerical analysis and calculations. It supports the same range of numbers as single-precision floating-point values (around 6 to 9 decimal digits) with more precision (about 15 to 16 decimal digits). Converting various elements within a cell into double format can simplify computations and visualizations, making it easier to analyze and interpret data.

There are several ways to convert cells to `double` type in MATLAB. In the following sections, we’ll explore different approaches to achieve this conversion efficiently:

### Using the ‘cell2double’ Function

The most straightforward method of converting a cell array to double is by utilizing the `cell2double` function, which automatically casts all elements within a given cell array into double format. Here’s how you can use it:

``````inputCell = {1, 4.5678, 'hello', [1 2], pi}; % Create an example cell containing various types
doubleCell = cell2double(inputCell); % Convert the elements of inputCell to double format
``````

In this code snippet:

• The original `inputCell` contains heterogeneous elements (numbers, strings, arrays, and a function).
• When passed as an argument to the `cell2double` function, all elements within `inputCell` will be converted into their double equivalents. The result will be stored in a new cell array named `doubleCell`.

### Converting Individual Cells or Elements Within Cell Arrays

If you only need to convert some specific cells or elements within a larger cell array, you can apply individual type conversion on these selected components. To do this, you should follow the same rules as regular numeric data types, such as converting numbers into strings using `num2str` or casting strings into numbers via `str2double`. Here are some examples of applying type conversions for specific cells:

``````inputCell = {1, '4.5678', 'hello', [1 2], pi}; % Create an example cell containing various types

% Convert the numeric elements into double
doubleCell = inputCell(1,2); % Double conversion for a specific element (indexing)
doubleCell{1,2} = str2double(inputCell{1,2}); % Double conversion for a specific element using str2double function

% Cast a string to double and assign it to an array element
doubleElement = str2double('4.5678');
inputCell{3,2,1} = doubleElement;
``````

In these examples:

• The original `inputCell` contains different data types as before.
• In the first code block, we demonstrate two ways of converting only the second element within `inputCell` (the number ‘4.5678’) to double format. This leaves the other elements untouched in their respective formats.
• The last example shows how you can convert a string (‘4.5678’) into its numeric equivalent using `str2double`, and then assign this value as the second element of the third column in cell array `inputCell`. This is another method to achieve cell conversion while preserving the original structure.

### Converting Cells with Custom Functions or Code Snippets

You can also implement custom functions or code blocks for handling data conversions within your MATLAB scripts, which provide greater flexibility and control over the type of conversion performed. For instance, you could define a function that returns all numeric elements in a cell as doubles:

``````function doubleElements = getDoubleElements(cellArray)
% This function extracts double-type elements from a given cell array
% Input: CellArray - A cell array containing different data types
% Output: DoubleElements - A cell array of double-type elements

nElem = numel(cellArray); % Get the number of elements in the input cell
doubleElements = zeros(nElem,1,'double'); % Create a new double-type cell to store the converted elements
for idx = 1:nElem
% Check if the current element is numeric and convert it to double
if isnumeric(cellArray{idx}) && isnan(cellArray{idx}) == false
doubleElements{idx} = str2double(num2str(cellArray{idx}));
end
end
``````

In this function:

• You’re given a cell array `CellArray`, which may contain any number of heterogeneous elements.
• The function iterates through each element, checks if it is numeric, and ensures that it doesn’t hold NaN values. For all numeric elements, we convert them to double by first casting the element to string (using `num2str`) and then using `str2double` to achieve double conversion.
• The final result is a cell array containing only the converted double elements from `CellArray`, which can be used in other functions or for further processing.

## Conclusion

In this comprehensive tutorial, we delved into the concept of converting cells into double format within MATLAB. We explored several approaches to achieve this conversion and provided practical examples with code snippets demonstrating different methods for implementing cell-to-double conversions in your scripts. By understanding these techniques, you can work more efficiently in MATLAB and ensure the best data analysis results for your computational needs.