shiftdata

Shift data to operate on specified dimension

Syntax

[y,perm,nshifts] = shiftdata(x,dim)

Description

[y,perm,nshifts] = shiftdata(x,dim) shifts data x to permute dimension dim to the first column using the same permutation as the built-in filter function. perm is the permutation that the function uses.

Note

Use the shiftdata function in tandem with the unshiftdata function, which shifts the data back to its original shape. These functions are useful for creating functions that work along a certain dimension, like filter, goertzel, sgolayfilt, and sosfilt.

Examples

Permute Dimensions of Magic Square

Shift a 3-by-3 magic square, permuting the second dimension to the first column. Shift the matrix back to its original shape.

Create a 3-by-3 magic square.

x = magic(3)

x = 3×3

     8     1     6
     3     5     7
     4     9     2

Shift the matrix to work along the second dimension. Return the permutation vector, the number of shifts, and the shifted matrix.

[x,perm,nshifts] = shiftdata(x,2)

x = 3×3

     8     3     4
     1     5     9
     6     7     2

perm = 1×2

     2     1

nshifts =

     []

Restore the matrix back to its original shape.

y = unshiftdata(x,perm,nshifts)

y = 3×3

     8     1     6
     3     5     7
     4     9     2

Rearrange Array to Operate on First Nonsingleton Dimension

Define the data to shift as a row vector.

x = 1:5

x = 1×5

     1     2     3     4     5

Define dim as empty to shift the first nonsingleton dimension of the data to the first column. shiftdata returns the data as a column vector, the permutation vector, and the number of shifts.

dim = [];
[x,perm,nshifts] = shiftdata(x,dim)

x = 5×1

     1
     2
     3
     4
     5

perm =

     []

nshifts = 
1

Restore the shifted data to its original shape.

y = unshiftdata(x,perm,nshifts)

y = 1×5

     1     2     3     4     5

Input Arguments

x — Data

vector | matrix

Data, specified as a vector or matrix.

Data Types: single | double

dim — Dimension to operate along

[] | positive integer

Dimension to operate along, specified as a positive integer or []. If dim is [], then the function shifts the first nonsingleton dimension to the first column and returns the number of shifts in nshifts.

Data Types: single | double

Output Arguments

y — Shifted data

vector | matrix

Shifted data, returned as a vector or matrix.

perm — Permutation

vector

Permutation used to shift the data, returned as a vector.

nshifts — Number of shifts

scalar

Number of shifts, returned as a scalar.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

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).

Version History

Introduced in R2012b

R2024b: shiftdata supports C/C++ code generation

The shiftdata function supports C/C++ code generation. You must have MATLAB^® Coder™ to use this functionality.