MATLAB: Multiple area access in cells

Question

dear ladies and gentlemen,

i have got another question. if i have a cell of arrays, e.g. …

>> D(:,1)
ans = 
    [3x3 double]
    [3x3 double]
    [3x3 double]

and every cell element (in this case arrays) containes double values like the first cell element does, …

    >> D{1}
ans =
   0.118997681558377   0.340385726666133   0.751267059305653
   0.498364051982143   0.585267750979777   0.255095115459269
   0.959743958516081   0.223811939491137   0.505957051665142

what comprehensible gives same result as , …

>> D{1,1}

well! and if have another cells of arrays, let us say e.q.: …

A = 
    [3x3 double]
    [3x3 double]
    [3x3 double]

with arrays like this: ..

    >> A{1}
ans =
     6     5     2
     8     1     8
     9     1     2

how can i reference my cells to rewirte e.q. every element in cell D and its every first column with first column of A, and

while doing so at the best without a loop or an if.

first, i thought on the colon operator, but i cant handle it. instead of allocate cell element by element with ..

>> D{1}(:,1)=A{1}(:,1)
>> D{2}(:,1)=A{1}(:,1)
a.s.o.

i tried …

>> D{:}(:,1)=A{1}(:,1)
and
>> D{1:3}(:,1)=A{1}(:,1)

without success.

can someone help me =) please

regards

Answer 1

If you want to keep your data as cell arrays you don't have a choice but to use an explicit loop:

for i = 1:numel(D)  
    D{i}(:, 1) = A{i}(:, 1);
end

However, since the matrices in your cell arrays are all the same size, you would be better off storing the whole lot as a 3D matrix. It's much easier to work with 3D matrices than cell arrays of 2D matrices. In particular, you could indeed do the copy in just one line

%convert cell array of 2D matrices into 3D matrix:
D = cat(3, D{:});
A = cat(3, A{:});
%replace 1st column of each page:
D(:, 1, :) = A(:, 1, :);