unshiftdata

Inverse of shiftdata

Syntax

y = unshiftdata(x,perm,nshifts)


Description

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.

Examples

Example 1

1. Create a 3-by-3 magic square:

   x = fi(magic(3))

   x = 
   
        8     1     6
        3     5     7
        4     9     2
   
             DataTypeMode: Fixed-point: binary point scaling
               Signedness: Signed
               WordLength: 16
           FractionLength: 11

2. Shift the matrix x to work along the second dimension:

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

   x = 
   
        8     3     4
        1     5     9
        6     7     2
   
             DataTypeMode: Fixed-point: binary point scaling
               Signedness: Signed
               WordLength: 16
           FractionLength: 11
   
   perm =
   
        2     1
   
   
   nshifts =
   
        []

   This command returns the permutation vector, perm, and the number of shifts, nshifts, are returned along with the shifted matrix, x.

3. Shift the matrix back to its original shape:

   y = unshiftdata(x,perm,nshifts)

   y = 
   
        8     1     6
        3     5     7
        4     9     2
   
             DataTypeMode: Fixed-point: binary point scaling
               Signedness: Signed
               WordLength: 16
           FractionLength: 11

Example 2

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,[])

   x =
   
        1
        2
        3
        4
        5
   
   
   perm =
   
        []
   
   
   nshifts =
   
        1

   This command returns x as a column vector, along with perm, the permutation vector, and nshifts, the number of shifts.

3. Using unshiftdata, restore x to its original shape:

   y = unshiftdata(x,perm,nshifts)

   y =
   
        1     2     3     4     5

Version History

Introduced in R2008a