3-D matrix operations

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Asmita Banerjee
Asmita Banerjee 2020-3-4
编辑： Matt J 2020-3-4
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!
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Asmita Banerjee
Asmita Banerjee 2020-3-4
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
Turlough Hughes 2020-3-4
"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

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采纳的回答

the cyclist
the cyclist 2020-3-4
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.

更多回答（2 个）

Turlough Hughes
Turlough Hughes 2020-3-4
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;
Matt J
Matt J 2020-3-4
编辑：Matt J 2020-3-4
Another guess,
result=convn(RefBlock,[1,1]/2,'valid');

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