num2cell - Convert array to cell array with consistently sized cells - MATLAB (original) (raw)

Convert array to cell array with consistently sized cells

Syntax

Description

[C](#btj8u9n-C) = num2cell([A](#btj8u9n-A)) converts arrayA into cell array C by placing each element of A into a separate cell inC.

The num2cell function converts an array that has any data type—even a nonnumeric type.

example

[C](#btj8u9n-C) = num2cell([A](#btj8u9n-A),[dim](#btj8u9n-dim)) splits the contents of A into separate cells of C, where dim specifies which dimensions of A to include in each cell. dim can be a scalar or a vector of dimensions. For example, if A has 2 rows and 3 columns, then:

num2cell(A,1) creates a 1-by-3 cell array C, where each cell contains a 2-by-1 column of A.
num2cell(A,2) creates a 2-by-1 cell array C, where each cell contains a 1-by-3 row of A.
num2cell(A,[1 2]) creates a 1-by-1 cell array C, where the cell contains the entire array A.

example

Examples

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Place all elements of a numeric array into separate cells.

a = 3×3

 8     1     6
 3     5     7
 4     9     2

c=3×3 cell array {[8]} {[1]} {[6]} {[3]} {[5]} {[7]} {[4]} {[9]} {[2]}

Place individual letters of a word into separate cells of an array.

a = ['four';'five';'nine']

a = 3×4 char array 'four' 'five' 'nine'

c = 3×4 cell {'f'} {'o'} {'u'} {'r'} {'f'} {'i'} {'v'} {'e'} {'n'} {'i'} {'n'} {'e'}

Generate a 4-by-3-by-2 numeric array, and then create a 1-by-3-by-2 cell array of 4-by-1 column vectors.

A = reshape(1:12,4,3); A(:,:,2) = A*10

A = A(:,:,1) =

 1     5     9
 2     6    10
 3     7    11
 4     8    12

A(:,:,2) =

10    50    90
20    60   100
30    70   110
40    80   120

C = 1×3×2 cell array C(:,:,1) =

{4×1 double}    {4×1 double}    {4×1 double}

C(:,:,2) =

{4×1 double}    {4×1 double}    {4×1 double}

Each 4-by-1 vector contains elements from along the first dimension of A:

Create a 4-by-1-by-2 cell array of 1-by-3 numeric arrays.

C = 4×1×2 cell array C(:,:,1) =

{[ 1 5 9]}
{[2 6 10]}
{[3 7 11]}
{[4 8 12]}

C(:,:,2) =

{[ 10 50 90]}
{[20 60 100]}
{[30 70 110]}
{[40 80 120]}

Each 1-by-3 row vector contains elements from along the second dimension of A:

Finally, create a 4-by-3 cell array of 1-by-1-by-2 numeric arrays.

C=4×3 cell array {1×1×2 double} {1×1×2 double} {1×1×2 double} {1×1×2 double} {1×1×2 double} {1×1×2 double} {1×1×2 double} {1×1×2 double} {1×1×2 double} {1×1×2 double} {1×1×2 double} {1×1×2 double}

Each 1-by-1-by-2 vector contains elements from along the third dimension of A:

ans = ans(:,:,1) =

ans(:,:,2) =

Create a cell array by combining elements into numeric arrays along several dimensions.

A = reshape(1:12,4,3); A(:,:,2) = A*10

A = A(:,:,1) =

 1     5     9
 2     6    10
 3     7    11
 4     8    12

A(:,:,2) =

10    50    90
20    60   100
30    70   110
40    80   120

c=1×3 cell array {4×1×2 double} {4×1×2 double} {4×1×2 double}

Each 4-by-1-by-2 array contains elements from along the first and third dimension of A:

ans = ans(:,:,1) =

ans(:,:,2) =

c=4×1 cell array {1×3×2 double} {1×3×2 double} {1×3×2 double} {1×3×2 double}

Input Arguments

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Input, specified as any type of multidimensional array.

Dimension of A, specified as a positive integer or a vector of positive integers. dim must be between 1 and ndims(A).

Elements do not need to be in numeric order. However, num2cell permutes the dimensions of the arrays in each cell of C to match the order of the specified dimensions.

Output Arguments

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Resulting array, returned as a cell array. The size of C depends on the size of A and the values of dim.

If dim is not specified, then C is the same size as A.
If dim is a scalar, thenC containsnumel(A)/size(A,dim) cells. Ifdim is 1 or 2, then each cell contains a column or row vector, respectively. If dim > 2, then each cell contains an array whose dimth dimensional length is size(A,dim), and whose other dimensions are all singletons.
For example, given a 4-by-7-by-3 array, A, this figure shows how num2cell creates cells corresponding to dim values of1, 2, and3.
If dim is a vector containingN values, then C hasnumel(A)/prod([size(A,dim(1)),...,size(A,dim(N))]) cells. Each cell contains an array whosedim (i)th dimension has a length of size(A,dim(i)) and whose other dimensions are singletons.
For example, given a 4-by-7-by-3 array, you can specifydim as a positive integer vector to create cell arrays of different dimensions.

Data Types: cell

Tips

To convert the cell array [C](#btj8u9n-C) back to an array, use the cell2mat function, or use the syntaxcat([dim](#btj8u9n-dim),C{:}) wheredim specifies the dimensions.

Extended Capabilities

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Usage notes and limitations:

Code generation does not support the dim input.

Version History

Introduced before R2006a