3-D matrix operations

I have a 5X126 matrix that I am splitting into a [5,21,6] matrix using reshape. I want to average the values of neighboring columns in each of these submatrices and store them into a final 3-d matrix that will be [5 20 6]. How can i write a for loop to do this?

I am very new to Matlab so any help would be appreciated. Thanks!

[KSSV]

What average/ mean you want? Check the dimensions of the output once.

[Asmita Banerjee]

RefBlock = reshape(FinalRef,5,21,m./21); %%breaking down matrix into separate blocks

SamBlock = reshape(FinalSam,5,20,n./20);

RefBloAvg = zeros(5,20,m./21);

for i = 1:20

for j = 1:(m./21)

RefBloAvg(:,i,j) = (FinalRef(:,i,j) + FinalRef(:,i+1,j))./2;

end

end

this is what I wrote to average neighboring values in my new sub-matrix but I get the error "Index in position 3 exceeds array bounds (must not exceed 1)."

[Turlough Hughes]

"I want to average the values of neighboring columns" is a little ambiguous, if we consider a smaller example, such as the following 5 by 5 matrix

>> M = randi(10,[5 5])

M =

     8     9     2     4     6
     1     8     1     5     9
     9     6    10     7     4
    10     2     4     1     5
    10     4     3     9     1

Is this the output you're expecting on each page as follows:

>> result = M(:,1:end-1) + diff(M,1,2)./2

result =

    8.5000    5.5000    3.0000    5.0000
    4.5000    4.5000    3.0000    7.0000
    7.5000    8.0000    8.5000    5.5000
    6.0000    3.0000    2.5000    3.0000
    7.0000    3.5000    6.0000    5.0000

Answer 1

[the cyclist]

Assuming that for the average of columns you want the result that Turlough specified, then

RefBloAvg = movmean(RefBlock,[0 1],2);
RefBloAvg(:,end,:) = [];

Note that this does not need to be in a loop of any kind. It works on the entire array at once.

[Asmita Banerjee]

this works! thank you!

Answer 2

[Turlough Hughes]

Here's the method I was suggesting. The idea is to take the first value and add half the difference (effectively interpolating)

RefBloAvg = RefBlock(:,1:end-1,:) + diff(RefBlock,1,2)./2;

Answer 3

[Matt J]

Another guess,

result=convn(RefBlock,[1,1]/2,'valid');