permute

Arguments

x

an array with any number of dimensions (0, 1, 2, or any number n>2), of any data type: booleans, integers, decimal real or complex numbers, polynomials, rationals, array of structures, array of cells.

dims

a valid permutation of 1:n>=nmin where n is the number of dimensions of the desired array, at least as many as nmin = ndims(x).

The dimension #i in y was the dimension #dims(i) in x.

y

an array with the contents of x, with identical but permuted sizes.

Description

Permutes the dimensions of the array according to dims.

Any trailing dimension of the result y that becomes a singleton (has a new size equal to 1, coming from a formerly non trailing singleton dimension) is automatically ignored (squeezed).

permute() is mainly interesting when dealing with hypermatrices. To only transpose a matrix (permute its rows into columns and vice-versa), the .' or ' operators should be prefered.

Examples

// Example 1: A matrix becomes an hypermatrix with one side of size==1
//            (here the number of rows)
x = [1 2 3; 4 5 6]
y = permute(x,[3 1 2])

--> x = [1 2 3; 4 5 6]
 x  =
   1.   2.   3.
   4.   5.   6.

--> y = permute(x,[3 1 2])
 y  =
(:,:,1)
   1.   4.
(:,:,2)
   2.   5.
(:,:,3)
   3.   6.

// Example 2: With encoded integers
x = int8(matrix(1:24, [3 4 2]))
y = permute(x, [2 3 1])

--> x = int8(matrix(1:24, [3 4 2]))
 x  =
(:,:,1)
  1  4  7  10
  2  5  8  11
  3  6  9  12
(:,:,2)
  13  16  19  22
  14  17  20  23
  15  18  21  24

--> y = permute(x, [2 3 1])
 y  =
(:,:,1)
  1  13
  4  16
  7  19
 10  22
(:,:,2)
  2  14
  5  17
  8  20
 11  23
(:,:,3)
  3  15
  6  18
  9  21
 12  24

// Example 3:
x = matrix(1:8, [2 1 4])
y = permute(x, [3 1 2]);
// The dimension 1 was the 3rd: size = 4 = new number of rows
// The dimension 2 was the 1st: size = 2 = new number of columns
// The dimension 3 was the 2sd: size = 1 = new number of pages
y

See also

• pertrans — Transposition with reference to the 2nd diagonal
• quote — (') transpose operator, string delimiter
• ndims — number of dimensions of an array
• squeeze — removes singleton dimensions of a ND-array

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