Inverse of shiftdata
y = unshiftdata(x,perm,nshifts)
y = unshiftdata(x,perm,nshifts) restores
the orientation of the data that was shifted with shiftdata.
The permutation vector is given by perm, and nshifts is
the number of shifts that was returned from shiftdata.
unshiftdata is meant to be used in tandem
with shiftdata. These functions are useful for
creating functions that work along a certain dimension, like filter, goertzel, sgolayfilt,
and sosfilt.
This example shifts x, a 3-by-3 magic
square, permuting dimension 2 to the first column. unshiftdata shifts x back
to its original shape.
1. Create a 3-by-3 magic square:
x = fi(magic(3))
x =
8 1 6
3 5 7
4 9 2
2. Shift the matrix x to work along the second
dimension:
[x,perm,nshifts] = shiftdata(x,2)
This command returns the permutation vector, perm,
and the number of shifts, nshifts, are returned
along with the shifted matrix, x:
x =
8 3 4
1 5 9
6 7 2
perm =
2 1
nshifts =
[]3. Shift the matrix back to its original shape:
y = unshiftdata(x,perm,nshifts)
y =
8 1 6
3 5 7
4 9 2
This example shows how shiftdata and unshiftdata work
when you define dim as empty.
1. Define x as a row vector:
x = 1:5
x =
1 2 3 4 5
2. Define dim as empty to shift the first
non-singleton dimension of x to the first column:
[x,perm,nshifts] = shiftdata(x,[])
This command returns x as a column vector,
along with perm, the permutation vector, and nshifts,
the number of shifts:
x =
1
2
3
4
5
perm =
[]
nshifts =
1
3. Using unshiftdata, restore x to
its original shape:
y = unshiftdata(x,perm,nshifts)
y =
1 2 3 4 5