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Cell Arrays in MATLAB

In this tutorial we will explain what MATLAB cell arrays are and how to work with them.

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Create a Cell Array

A cell array is a data type that can hold different types or sizes of data in each cell.

Use curly braces { } to define cells, separating entries by commas or spaces, and rows by semicolons.

Define a 1×3 cell array

C = {'text', 42, [1,2,3]}

	1	2	3
1	'text'	42	[1,2,3]

Define a 2×2 cell array

C2 = { 'pi',    pi; ...
    'matrix', [1 2;3 4] }

	1	2
1	'pi'	3.1416
2	'matrix'	[1,2;3,4]

Use parentheses ( ) to extract a cell (returns a cell), and curly braces { } to extract its contents.

Extract a 1×1 cell

cell1 = C(2)

cell1 = 1x1 cell array
    {[42]}

Extract the content (numeric 42)

value42 = C{2}

value42 = 42

Access part of the matrix inside cell

subval = C2{2,2}(1,2)

subval = 2

Assign into cells with curly braces { } to overwrite contents, or with parentheses ( ) to overwrite cell itself.

Change the second cell content to a string

C{2} = 'answer'

	1	2	3
1	'text'	'answer'	[1,2,3]

Replace entire cell with another cell

C(3) = {ones(3)}

	1	2	3
1	'text'	'answer'	[1,1,1;1,1,1;1,1,1]

Add a new cell at the end

C{4} = @sin

	1	2	3	4
1	'text'	'answer'	[1,1,1;1,1,1;1,1,1]	@sin

Cells can contain other cell arrays for hierarchical storage.

Create nested cell

Cnested = { 'level1', { 'level2', { 100, 200 } } }

	1	2
1	'level1'	1x2 cell

Access deeply nested value 200

deep200 = Cnested{2}{2}{2}

deep200 = 200

You can convert between numeric arrays and cells when dimensions match.

Numeric array

A = [10, 20;
     30, 40]

A = 2x2
    10    20
    30    40

Convert to cell array

Acell = num2cell(A)

	1	2
1	10	20
2	30	40

Convert back to numeric (if all cells contain scalars)

Anum = cell2mat(Acell)

Anum = 2x2
    10    20
    30    40