flipdim
reverses the order of (blocks of) rows, columns, pages.. of an array
Syntax
y = flipdim(x, dim) y = flipdim(x, dim, blockSize)
Arguments
- x, y
vectors, matrices, or hypermatrices of any regular data type, or cells array.
y
gets the sizes ofx
.- dim
positive integer : index of the dimension / direction of
x
along which the order ofx
components must be inverted.- blockSize
a positive integer, sub-multiple of
size(x,dim)
: number of rows, of columns, of pages etc in each block. Default value = 1
Description
flipdim(x, 1)
inverts the order of
rows of x
.
flipdim(x, 2)
inverts the order of
columns of x
.
flipdim(x, 3)
inverts the order of
pages of x
. Etc.
The optional parameter blockSize
allows splitting
x
in size(x,1)/blockSize
blocks
of blockSize
rows (dim=1
),
or in size(x,2)/blockSize
blocks of blockSize
columns (dim=2
), etc (dim>2
)
and to invert their order.
In each block, the order of components (rows, columns, pages etc)
is unchanged.
Examples
// Example 1: flip x rows (= components along the first dimension) x = [1 2 3 4; 5 6 7 8] y = flipdim(x, 1) // Example 2: flip x columns (= components along the second dimension) y = flipdim(x, 2) // Example 3: flip x pages (= components along the third dimension) x = matrix(1:24, [3 2 4]) y = flipdim(x, 3) // Example 4: the first example with complex x = [1+%i 2*%i 3 4; 5 6-%i 7 8*%pi*%i] y = flipdim(x, 1) // Integer-encoded numbers: x = int16(grand(4, 3, 2, "uin", -9, 9)) y = flipdim(x, 1) // Booleans: x = (grand(3, 4, "uin", -9, 9) > 0) y = flipdim(x, 2) // Texts: x = matrix(strsplit("a":"x", 1:23), 4, 6); x = x+x flipdim(x, 2) // Polynomials: x = inv_coeff(grand(3, 9, "uin", 0, 3), 2) flipdim(x, 1) // Rationals: n = inv_coeff(grand(3, 9, "uin", 0, 3), 2); d = inv_coeff(grand(3, 9, "uin", 0, 3), 2); d(d == 0) = 1; r = n./d flipdim(r, 2)
Examples using blockSize
:
X = [0 1 2 3 4 5 6 7 8 9 10 11]; flipdim(X, 2, 2) // => [10 11 8 9 6 7 4 5 2 3 0 1] // Block size = 2. flipdim(X, 2, 3) // => [9 10 11 6 7 8 3 4 5 0 1 2] flipdim(X, 2, 4) // => [8 9 10 11 4 5 6 7 0 1 2 3] flipdim(X, 2, 6) // => [6 7 8 9 10 11 0 1 2 3 4 5] // Error if blockSize does not divide the targeted dimension of x. try y = flipdim(X, 2, 5); // size(X) = [1 12] and blockSize=5 does not divide 12. catch disp("size(X) = [1 12] and blockSize=5 does not divide 12"); end
Example of results:
--> x x = -5 -2 0 9 0 -7 -6 9 -1 -8 -7 8 --> flipdim(x, 1) ans = -1 -8 -7 8 0 -7 -6 9 -5 -2 0 9 --> flipdim(x, 2) ans = 9 0 -2 -5 9 -6 -7 0 8 -7 -8 -1
--> x x = (:,:,1) 9 4 -3 -4 -8 -3 (:,:,2) 5 8 9 4 4 9 --> flipdim(x, 3) ans = (:,:,1) 5 8 9 4 4 9 (:,:,2) 9 4 -3 -4 -8 -3
--> x x = -2 3 -5 9 -4 -8 2 8 4 -9 6 -6 -9 8 3 4 -3 4 --> flipdim(x, 2, 2) ans = -4 -8 -5 9 -2 3 6 -6 4 -9 2 8 -3 4 3 4 -9 8 --> flipdim(x, 2, 3) ans = 9 -4 -8 -2 3 -5 -9 6 -6 2 8 4 4 -3 4 -9 8 3
See also
- circshift — circularly shifts elements or subarrays of an array (regular, of structures, cells, custom)
- fftshift — rearranges the fft output, moving the zero frequency to the center of the spectrum
- ifftshift — inverse of fftshift
- colon — Ranging operator. Addresses all elements along an array dimension or of a list.
History
Version | Description |
5.5.0 |
|
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