sum every 2 pages at a time in 3D matrix

I'm trying to sum every 2 pages at a time in 3D data.

for example, suppose I have 3x2x5 double data like this:

data = ones(3,2,5);

after I sum every 2 pages then I can get 3x2x3 double data like this:

data(:,:,1) =

     2     2
     2     2
     2     2

data(:,:,2) =

     2     2
     2     2
     2     2

data(:,:,3) =

     1     1
     1     1
     1     1

I'm not sure you can understand what I'm saying..please leave comment if you need more explanation.

The JPG file I attached(pic.jpg) might help you understand.

Many thanks to all

Answer 1

[James Tursa]

Another way:

p = 2; % number of pages at a time to sum
datas = data;
m = mod(size(datas,3),p);
if( m )
    datas(end,end,end+p-m) = 0; % pad if needed
end
datas = reshape(datas,size(datas,1),size(datas,2),p,size(datas,3)/p);
result = sum(datas,3);
result = reshape(result,size(data,1),size(data,2),[]);

Answer 2

[Rik]

The code below isn't the most efficient for your example, but will work in more complicated situations.

data = ones(3,2,5);
k=2;%number of last dimension to be summed

d=numel(size(data));sumdata_part=cell(k,1);
for k2=1:k
    % This part doesn't support other dimensional examples,
    % but that can be done as well if you need it to.
    sumdata_part{k2}=data(:,:,k2:k:end);
end
%ensure same sizes
temp=zeros(size(sumdata_part{1}));
temp(1:numel(sumdata_part{end}))=sumdata_part{end};
sumdata_part{end}=temp;

%concatenate in a new direction and sum over that dimension
outcome=sum(cat(d+1,sumdata_part{:}),d+1)