repmat

Repeat copies of array

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

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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 | datetime | duration | calendarDuration | categorical | 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))

Compatibility Considerations

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Behavior changed in R2019b