repelem
Repeat copies of array elements
Description
,
where u
= repelem(v
,n
)v
is a scalar or vector, returns a vector
of repeated elements of v
.
If
n
is a scalar, then each element ofv
is repeatedn
times. The length ofu
islength(v)*n
.If
n
is a vector, then it must be the same length asv
. Each element ofn
specifies the number of times to repeat the corresponding element ofv
.
This syntax is not supported for table
input.
returns
an array with each element of B
= repelem(A
,r1,...,rN
)A
repeated according
to r1,...,rN
. Each r1,...,rN
must
either be a scalar or a vector with the same length as A
in
the corresponding dimension. For example, if A
is
a matrix, repelem(A,2,3)
returns a matrix containing
a 2
-by-3
block of each element
of A
.
Examples
Repeat Vector Elements
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
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
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
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
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 scalar
or a vector. If n
is a scalar, then all elements
of v
are repeated n
times. If n
is
a vector, then each element of n
specifies the
number 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 separate
arguments of integer-valued scalars or vectors. If A
is
a table, each repetition factor must be a scalar.
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
Output Arguments
u
— Output vector
vector
Output vector. If v
is a row vector or scalar, u
is
a row vector. If v
is a column vector, u
is
also 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 must be 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 cannot be 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™.
The repelem
function
fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray
(Parallel Computing Toolbox). 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
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