Repeat copies of array elements

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## Syntax

`u = repelem(v,n)`

`B = repelem(A,r1,...,rN)`

## Description

example

`u = repelem(v,n)`

,where `v`

is a scalar or vector, returns a vectorof repeated elements of `v`

.

If

`n`

is a scalar, then each elementof`v`

is repeated`n`

times. Thelength of`u`

is`length(v)*n`

.If

`n`

is a vector, then it mustbe the same length as`v`

. Each element of`n`

specifiesthe number of times to repeat the corresponding element of`v`

.

This syntax is not supported for `table`

input.

example

`B = repelem(A,r1,...,rN)`

returnsan array with each element of `A`

repeated accordingto `r1,...,rN`

. Each `r1,...,rN`

musteither be a scalar or a vector with the same length as `A`

inthe corresponding dimension. For example, if `A`

isa matrix, `repelem(A,2,3)`

returns a matrix containinga `2`

-by-`3`

block of each elementof `A`

.

## Examples

collapse all

### Repeat Vector Elements

Open Live Script

Create a vector and repeat each of its elements three times into a new vector.

v = [1 2 3 4];u = repelem(v,3)

`u = `*1×12* 1 1 1 2 2 2 3 3 3 4 4 4

Repeat the first two elements of `v`

twice and the last two elements three times.

u = repelem(v,[2 2 3 3])

`u = `*1×10* 1 1 2 2 3 3 3 4 4 4

### Repeat Matrix Elements

Open Live Script

Create a matrix and repeat each element into a 3-by-2 block of a new matrix.

A = [1 2; 3 4]

`A = `*2×2* 1 2 3 4

B = repelem(A,3,2)

`B = `*6×4* 1 1 2 2 1 1 2 2 1 1 2 2 3 3 4 4 3 3 4 4 3 3 4 4

### Repeat Matrix Columns

Open Live Script

Create a matrix and copy its columns into a new array, repeating the first column twice and second column three times.

A = [1 2; 3 4]

`A = `*2×2* 1 2 3 4

B = repelem(A,1,[2 3])

`B = `*2×5* 1 1 2 2 2 3 3 4 4 4

### Combine Vector Elements

Open Live Script

Create two column vectors.

A = [1; 3; 5];B = [2; 4];

Generate all element combinations of the two vectors by using `repelem`

and `repmat`

. Each row of the output `T`

is a combination with the first element coming from the first vector and the second element coming from the second vector. This command is equivalent to finding the Cartesian product of two vectors.

T = [repelem(A,numel(B)) repmat(B,numel(A),1)]

`T = `*6×2* 1 2 1 4 3 2 3 4 5 2 5 4

Starting in R2023a, you can also use the combinations function to generate all element combinations of two vectors.

T = combinations(A,B)

`T=`*6×2 table* A B _ _ 1 2 1 4 3 2 3 4 5 2 5 4

## Input Arguments

collapse all

`v`

— Input element

scalar | vector

Input element, specified as a scalar or a vector.

**Data Types: **`single`

| `double`

| `int8`

| `int16`

| `int32`

| `int64`

| `uint8`

| `uint16`

| `uint32`

| `uint64`

| `logical`

| `char`

| `string`

| `struct`

| `table`

| `cell`

| `datetime`

| `duration`

**Complex Number Support: **Yes

`n`

— Number of times to repeat each element

scalar | vector

Number of times to repeat each element, specified as a scalaror a vector. If `n`

is a scalar, then all elementsof `v`

are repeated `n`

times. If `n`

isa vector, then each element of `n`

specifies thenumber of times to repeat the corresponding element of `v`

.In either case, `n`

must be integer-valued.

**Data Types: **`single`

| `double`

| `int8`

| `int16`

| `int32`

| `int64`

| `uint8`

| `uint16`

| `uint32`

| `uint64`

`A`

— Input array

matrix | multidimensional array

Input array, specified as a matrix or multidimensional array.

**Data Types: **`single`

| `double`

| `int8`

| `int16`

| `int32`

| `int64`

| `uint8`

| `uint16`

| `uint32`

| `uint64`

| `logical`

| `char`

| `struct`

| `table`

| `cell`

| `datetime`

| `duration`

**Complex Number Support: **Yes

`r1,...,rN`

— Repetition factors for each dimension (as separate arguments)

scalars | vectors

Repetition factors for each dimension, specified as separatearguments of integer-valued scalars or vectors. If `A`

isa table, each repetition factor must be a scalar.

**Data Types: **`single`

| `double`

| `int8`

| `int16`

| `int32`

| `int64`

| `uint8`

| `uint16`

| `uint32`

| `uint64`

## Output Arguments

collapse all

`u`

— Output vector

vector

Output vector. If `v`

is a row vector or scalar, `u`

isa row vector. If `v`

is a column vector, `u`

isalso a column vector.

**Data Types: **`single`

| `double`

| `int8`

| `int16`

| `int32`

| `int64`

| `uint8`

| `uint16`

| `uint32`

| `uint64`

| `logical`

| `char`

| `string`

| `struct`

| `table`

| `cell`

| `datetime`

| `duration`

`B`

— Output array

matrix | multidimensional array

Output array, returned as a matrix or multidimensional array.

**Data Types: **`single`

| `double`

| `int8`

| `int16`

| `int32`

| `int64`

| `uint8`

| `uint16`

| `uint32`

| `uint64`

| `logical`

| `char`

| `string`

| `struct`

| `table`

| `cell`

| `datetime`

| `duration`

## Extended Capabilities

### Tall Arrays

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

This function supports tall arrays with the limitations:

The two-input syntax is not supported.

The replication factor in the first dimension mustbe 1. For example,

`repelem(TA,1,n,p,...)`

.

For more information, see Tall Arrays.

### C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

The input must be a vector or matrix. The input cannotbe a multidimensional array.

### GPU Code Generation

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

Usage notes and limitations:

The input must be a vector or matrix. The input cannot be a multidimensional array.

### 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, see Run 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, see Run 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, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

## Version History

**Introduced in R2015a**

## See Also

kron | repmat

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