reshape

Reshape array

Syntax

B = reshape(A,sz)

B = reshape(A,sz1,...,szN)

Description

B= reshape(A,sz)reshapesAusing the size vector,sz, to definesize(B). For example,reshape(A,[2,3])reshapesAinto a 2-by-3 matrix.szmust contain at least 2 elements, andprod(sz)must be the same asnumel(A).

example

B= reshape(A,sz1,...,szN)reshapesAinto asz1-by-...-by-szNarray wheresz1,...,szNindicates the size of each dimension. You can specify a single dimension size of[]to have the dimension size automatically calculated, such that the number of elements inBmatches the number of elements inA. For example, ifAis a 10-by-10 matrix, thenreshape(A,2,2,[])reshapes the 100 elements ofA成2 2-25 array.

Examples

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Reshape Vector into Matrix

Open Live Script

Reshape a 1-by-10 vector into a 5-by-2 matrix.

A = 1:10; B = reshape(A,[5,2])

B =5×21 6 2 7 3 8 4 9 5 10

Reshape Matrix to Have Specified Number of Columns

Open Live Script

Reshape a 4-by-4 square matrix into a matrix that has 2 columns. Specify[]for the first dimension to letreshapeautomatically calculate the appropriate number of rows.

A = magic(4)

A =4×416 2 3 13 5 11 10 8 9 7 6 12 4 14 15 1

B = reshape(A,[],2)

B =8×216 3 5 10 9 6 4 15 2 13 11 8 7 12 14 1

The result is an 8-by-2 matrix, which maintains the same number of elements as the original matrix. The elements inBalso maintain their columnwise order fromA.

Reshape Multidimensional Array into Matrix

Open Live Script

Reshape a 3-by-2-by-3 array of zeros into a 9-by-2 matrix.

A = zeros(3,2,3); B = reshape(A,9,2)

B =9×20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Input Arguments

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`A`—Input array
vector|matrix|multidimensional array

Input array, specified as a vector, matrix, or multidimensional array.

`sz`—Output size
row vector of integers

Output size, specified as a row vector of integers. Each element ofszindicates the size of the corresponding dimension inB. You must specifyszso that the number of elements inAandBare the same. That is,prod(sz)must be the same asnumel(A).

Beyond the second dimension, the output,B, does not reflect trailing dimensions with a size of1. For example,reshape(A,[3,2,1,1])produces a 3-by-2 matrix.

Example:reshape(A,[3,2])

Example:reshape(A,[6,4,10])

Example:reshape(A,[5,5,5,5])

`sz1,...,szN`—Size of each dimension
two or more integers|`[]`(optional)

Size of each dimension, specified as two or more integers with at most one[](optional). You must specify at least 2 dimension sizes, and at most one dimension size can be specified as[], which automatically calculates the size of that dimension to ensure thatnumel(B)matchesnumel(A). When you use[]to automatically calculate a dimension size, the dimensions that youdoexplicitly specify must divide evenly into the number of elements in the input matrix,numel(A).

Beyond the second dimension, the output,B, does not reflect trailing dimensions with a size of1. For example,reshape(A,3,2,1,1)produces a 3-by-2 matrix.

Example:reshape(A,3,2)

Example:reshape(A,6,[],10)

Example:reshape(A,2,5,3,[])

Example:reshape(A,5,5,5,5)

Output Arguments

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`B`— Reshaped array
vector | matrix | multidimensional array | cell array

Reshaped array, returned as a vector, matrix, multidimensional array, or cell array. The data type and number of elements inBare the same as the data type and number of elements inA. The elements inBpreserve their columnwise ordering fromA.

Extended Capabilities

Tall Arrays
Calculate with arrays that have more rows than fit in memory.

This function supports tall arrays with the limitations:

Reshaping the tall dimension (dimension one) is not supported. The first dimension input should always be empty, such asreshape(X,[],M,N,...).

For more information, seeTall Arrays for Out-of-Memory Data.

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

If the input is a compile-time empty cell array, then the size arguments must be constants.
Size arguments must have a fixed size.
SeeVariable-Sizing Restrictions for Code Generation of Toolbox Functions(MATLAB Coder).
For sparse matrices, thereshapefunction does not support trailing ones as inputs after the first two dimensions.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Usage notes and limitations:

If the input is a compile-time empty cell array, then the size arguments must be constants.
Size arguments must have a fixed size.
For sparse matrices, thereshapefunction does not support trailing ones as inputs after the first two dimensions.

HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

Thread-Based Environment
Run code in the background using MATLAB®`backgroundPool`or accelerate code with Parallel Computing Toolbox™`ThreadPool`.

This function fully supports thread-based environments. For more information, seeRun MATLAB Functions in Thread-Based Environment.

GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

This function fully supports GPU arrays. For more information, seeRun MATLAB Functions on a GPU(Parallel Computing Toolbox).

Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, seeRun MATLAB Functions with Distributed Arrays(Parallel Computing Toolbox).

Version History

Introduced before R2006a

reshape

Syntax

Description

Examples

Reshape Vector into Matrix

Reshape Matrix to Have Specified Number of Columns

Reshape Multidimensional Array into Matrix

Input Arguments

A—Input arrayvector|matrix|multidimensional array

sz—Output sizerow vector of integers

sz1,...,szN—Size of each dimensiontwo or more integers|[](optional)

Output Arguments

B— Reshaped arrayvector | matrix | multidimensional array | cell array

Extended Capabilities

Tall ArraysCalculate with arrays that have more rows than fit in memory.

C/C++ Code GenerationGenerate C and C++ code using MATLAB® Coder™.

GPU Code GenerationGenerate CUDA® code for NVIDIA® GPUs using GPU Coder™.

HDL Code GenerationGenerate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

Thread-Based EnvironmentRun code in the background using MATLAB®backgroundPoolor accelerate code with Parallel Computing Toolbox™ThreadPool.

GPU ArraysAccelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

Distributed ArraysPartition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

Version History

See Also

`A`—Input array
vector|matrix|multidimensional array

`sz`—Output size
row vector of integers

`sz1,...,szN`—Size of each dimension
two or more integers|`[]`(optional)

`B`— Reshaped array
vector | matrix | multidimensional array | cell array

Tall Arrays
Calculate with arrays that have more rows than fit in memory.

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

Thread-Based Environment
Run code in the background using MATLAB®`backgroundPool`or accelerate code with Parallel Computing Toolbox™`ThreadPool`.

GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.