circshift - Shift array circularly - MATLAB (original) (raw)

Syntax

Description

Y = circshift([A](#bt5nt1s-1-A),[K](#bt5nt1s-1-K)) circularly shifts the elements in array A by K positions. If K is an integer, then circshift shifts along the first dimension of A whose size does not equal 1. If K is a vector of integers, then each element of K indicates the shift amount in the corresponding dimension of A.

Note

The default behavior of circshift(A,K) where K is a scalar changed in R2016b. To preserve the behavior of R2016a and previous releases, use circshift(A,K,1). This syntax specifies 1 as the dimension to operate along.

example

Y = circshift([A](#bt5nt1s-1-A),[K](#bt5nt1s-1-K),[dim](#bt5nt1s-1-dim)) circularly shifts the values in array A by K positions along dimension dim. Inputs K and dim must be scalars.

example

Examples

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Create a numeric column vector.

A = 10×1

Use circshift to shift the elements by three positions.

Y = 10×1

The result, Y, has the same elements as A but they are in a different order.

Create an array of characters and use circshift to shift the characters by 3 positions. The characters are in a different order in Y.

A = 'racecar';
Y = circshift(A,3)

Create a numeric array with a cluster of ones in the top left.

A = [1 1 0 0; 1 1 0 0; 0 0 0 0; 0 0 0 0]

A = 4×4

 1     1     0     0
 1     1     0     0
 0     0     0     0
 0     0     0     0

Use circshift to shift each column of A one position to the right.

Y = 4×4

 0     1     1     0
 0     1     1     0
 0     0     0     0
 0     0     0     0

Shift the elements of A by one position in each dimension. The cluster of ones is now in the center of the matrix.

Y = 4×4

 0     0     0     0
 0     1     1     0
 0     1     1     0
 0     0     0     0

To move the cluster back to its original position, use circshift on Y with negative shift values. The matrix X is equivalent to A.

X = 4×4

 1     1     0     0
 1     1     0     0
 0     0     0     0
 0     0     0     0

Input Arguments

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

Shift amount, specified as an integer scalar or vector of integers.

If you specify K as an integer and do not specify dim, then circshift shifts along the first dimension whose size does not equal 1. Positive K shifts toward the end of the dimension and negative K shifts toward the beginning.
If you specify K as a vector of integers, then the _N_th element in K specifies the shift amount for the _N_th dimension in A. If the _N_th element in K is positive, then the values of A shift toward the end of the _N_th dimension. If the _N_th element is negative, then the values shift toward the beginning.

If the shift amount is greater than the length of the corresponding dimension in A, then the shift circularly wraps to the beginning of that dimension. For example, shifting a 3-element vector by +3 positions brings its elements back to their original positions.

Dimension to operate along, specified as a positive integer scalar. If no value is specified, the default is the first dimension whose size does not equal 1. If you specify dim, then K must be an integer scalar. In general, specify dim = 1 to exchange rows, dim = 2 to exchange columns, and so on.

Extended Capabilities

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Usage notes and limitations:

Code generation does not support tables and cells for the first input argument.

The circshift 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).

Version History

Introduced before R2006a