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repmat

Repeat copies of array

Syntax

B = repmat(A,n)
B = repmat(A,r1,...,rN)
B = repmat(A,r)

Description

example

B = repmat(A,n) returns an array containing n copies of A in the row and column dimensions. The size of B is size(A)*n when A is a matrix.

example

B = repmat(A,r1,...,rN) specifies a list of scalars, r1,..,rN, that describes how copies of A are arranged in each dimension. When A has N dimensions, the size of B is size(A).*[r1...rN]. For example, repmat([1 2; 3 4],2,3) returns a 4-by-6 matrix.

example

B = repmat(A,r) specifies the repetition scheme with row vector r. For example, repmat(A,[2 3]) returns the same result as repmat(A,2,3).

Examples

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Create a 3-by-2 matrix whose elements contain the value 10.

A = repmat(10,3,2)
A = 3×2

    10    10
    10    10
    10    10

Repeat copies of a matrix into a 2-by-2 block arrangement.

A = diag([100 200 300])
A = 3×3

   100     0     0
     0   200     0
     0     0   300

B = repmat(A,2)
B = 6×6

   100     0     0   100     0     0
     0   200     0     0   200     0
     0     0   300     0     0   300
   100     0     0   100     0     0
     0   200     0     0   200     0
     0     0   300     0     0   300

Repeat copies of a matrix into a 2-by-3 block arrangement.

A = diag([100 200 300])
A = 3×3

   100     0     0
     0   200     0
     0     0   300

B = repmat(A,2,3)
B = 6×9

   100     0     0   100     0     0   100     0     0
     0   200     0     0   200     0     0   200     0
     0     0   300     0     0   300     0     0   300
   100     0     0   100     0     0   100     0     0
     0   200     0     0   200     0     0   200     0
     0     0   300     0     0   300     0     0   300

Repeat copies of a matrix into a 2-by-3-by-2 block arrangement.

A = [1 2; 3 4]
A = 2×2

     1     2
     3     4

B = repmat(A,[2 3 2])
B = 
B(:,:,1) =

     1     2     1     2     1     2
     3     4     3     4     3     4
     1     2     1     2     1     2
     3     4     3     4     3     4


B(:,:,2) =

     1     2     1     2     1     2
     3     4     3     4     3     4
     1     2     1     2     1     2
     3     4     3     4     3     4

Vertically stack a row vector four times.

A = 1:4;
B = repmat(A,4,1)
B = 4×4

     1     2     3     4
     1     2     3     4
     1     2     3     4
     1     2     3     4

Horizontally stack a column vector four times.

A = (1:3)';  
B = repmat(A,1,4)
B = 3×4

     1     1     1     1
     2     2     2     2
     3     3     3     3

Create a table with variables Age and Height.

A = table([39; 26],[70; 63],'VariableNames',{'Age' 'Height'})
A=2×2 table
    Age    Height
    ___    ______

    39       70  
    26       63  

Repeat copies of the table into a 2-by-3 block format.

B = repmat(A,2,3)
B=4×6 table
    Age    Height    Age_1    Height_1    Age_2    Height_2
    ___    ______    _____    ________    _____    ________

    39       70       39         70        39         70   
    26       63       26         63        26         63   
    39       70       39         70        39         70   
    26       63       26         63        26         63   

repmat repeats the entries of the table and appends a number to the new variable names.

Input Arguments

collapse all

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

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char | string | struct | table | cell
Complex Number Support: Yes

Number of times to repeat the input array in the row and column dimensions, specified as an integer value. If n is 0 or negative, the result is an empty array.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Repetition factors for each dimension, specified as separate arguments of integer values. If any repetition factor is 0 or negative, the result is an empty array.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Vector of repetition factors for each dimension, specified as a row vector of integer values. If any value in r is 0 or negative, the result is an empty array.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Tips

  • To build block arrays by forming the tensor product of the input with an array of ones, use kron. For example, to stack the row vector A = 1:3 four times vertically, you can use B = kron(A,ones(4,1)).

  • To create block arrays and perform a binary operation in a single pass, use bsxfun. In some cases, bsxfun provides a simpler and more memory efficient solution. For example, to add the vectors A = 1:5 and B = (1:10)' to produce a 10-by-5 array, use bsxfun(@plus,A,B) instead of repmat(A,10,1) + repmat(B,1,5).

  • When A is a scalar of a certain type, you can use other functions to get the same result as repmat.

    repmat SyntaxEquivalent Alternative
    repmat(NaN,m,n)NaN(m,n)
    repmat(single(inf),m,n)inf(m,n,'single')
    repmat(int8(0),m,n)zeros(m,n,'int8')
    repmat(uint32(1),m,n)ones(m,n,'uint32')
    repmat(eps,m,n)eps(ones(m,n))

Extended Capabilities

Introduced before R2006a