reshape a matrix in a special manner

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Rica
Rica 2012-11-26
Hi!
how could i make this matrix reschaping:
% A=[A(:,1) A(:,2) A(:,3).....A(:,130)]
TO
C1= mean([A(:,1)....A(:,10)],2)
C2=mean([A(:,11)........A(:,20)],2)
C3=mean([A(:,21)........A(:,30)],2)
C=[C1 C2 C3..........C13]
Thank you

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采纳的回答

Pedro Villena
Pedro Villena 2012-11-26
编辑：Pedro Villena 2012-11-26
A = rand(100,130);
step = 10;
C = cell2mat(arrayfun(@(i,j) mean(A(:,i:j),2),...
1:step:length(A)-step, 1+step:step:length(A),'un',0))

更多回答（3 个）

José-Luis
José-Luis 2012-11-26
编辑：José-Luis 2012-11-26
Faster:
a = rand(100,130);
[m n] = size(a);
a = reshape(a,m,10,n/10); %Provided n is divisible by 10
your_mat = squeeze(mean(a,2));
One liner of the above:
your_mat = squeeze(mean(reshape(a,size(a,1),10,size(a,2)/10),2));
Matt J
Matt J 2012-11-26
Using the function below
downsampn(A,[size(A,1),10]);
function M=downsampn(M,bindims)
%DOWNSAMPN - simple tool for downsampling n-dimensional nonsparse arrays
%
% M=downsampn(M,bindims)
%
%in:
%
% M: an array
% bindims: a vector of integer binning dimensions
%
%out:
%
% M: the downsized array
nn=length(bindims);
[sz{1:nn}]=size(M); %M is the original array
sz=[sz{:}];
newdims=sz./bindims;
args=num2cell([bindims;newdims]);
M=reshape(M,args{:});
for ii=1:nn
M=mean(M,2*ii-1);
end
M=reshape(M,newdims);
Matt J
Matt J 2012-11-26
m=mean(reshape(A,[],10,13),2);
reshape(m,[],13);

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