Remove dimension from high dimensional array

Hi all, I have a 8D array with size 10 8 10 8 6 7 8 9, and I want to remove one specific dimension (the one with 6 elements), obtaining a 7D array. There exist a Matlab function to do it?

Answer 1

[Scott MacKenzie]

Try this...

M = rand(10, 8, 10, 8, 6, 7, 8, 9);
whos

  Name      Size                Bytes  Class     Attributes

  M         8-D             154828800  double              

M(:,:,:,:,2:end,:,:,:) = [];
N = squeeze(M);
whos

  Name      Size               Bytes  Class     Attributes

  M         8-D             25804800  double              
  N         7-D             25804800  double              

[Francesco Porretta]

It works for me, thanks a lot!

[Scott MacKenzie]

You're welcome. Good luck.

[Shaun Lalani]

Hi Scott, can you please explain why you used 2:end instead of 1:end?

[Scott MacKenzie]

That's an interesting question. Think about this for a n x m 2D matrix -- a matrix with n rows and m columns. You can't simply remove all the rows and have only the columns left. If you remove all the rows, nothing is left. You need to keep one of the rows, leaving a 1 x m "matrix"; i.e., a 1D matrix or vector.

Using 2:end in my solution is equivalent to

M(:,:,:,:,[2 3 4 5 6],:,:,:) = [];

This leaves all the data for the other dimensions that are associated with the 1st position in the 5th dimension. You could also use

M(:,:,:,:,[1 3 4 5 6],:,:,:) = [];

The resulting matrx, M, would have a different collection of data. It would have all the data from the other dimensions that are associated with the 2nd position in the 5th dimenion. Which position to choose in the 5th dimension is a matter of what the data represent and what the objectives are.