replace part of matrix to another matrix

Question

mohammed hussein 2017-11-18

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https://ww2.mathworks.cn/matlabcentral/answers/367853-replace-part-of-matrix-to-another-matrix

评论： mohammed hussein 2017-11-19

Hi i have many matrices in same size , i want to add all of them together in one matrix with replace the last quarter of each one to binning of next one until complete the matrix and the rest will be zeros . for example

a =zeros(5,5)
A=[1 2 ;3 4];
B=[5 6;7 8];
C=[9 10;11 12];
D=[13 14;15 16];

the answer

a=
   2     0     0     0
   5     6     0     0
   7     9    10     0
   0    11    13    14
   0     0    15    16

thank you very much for helping

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Answer 1

Stephen23 2017-11-18

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https://ww2.mathworks.cn/matlabcentral/answers/367853-replace-part-of-matrix-to-another-matrix#answer_291893

编辑：Stephen23 2017-11-18

在 MATLAB Online 中打开

For any size matrices, even combinations of different sizes:

C = {[1,2;3,4],[5,6;7,8],[9,10;11,12],[13,14;15,16]};
num = numel(C);
szr = cellfun('size',C,1);
szc = cellfun('size',C,2);
csr = cumsum([0,szr-1]);
csc = cumsum([0,szc-1]);
M = zeros(1+csr(end),1+csc(end));
for k = 1:num
  idr = csr(k)+(1:szr(k));
  idc = csc(k)+(1:szc(k));
  M(idr,idc) = C{k};
end

Giving:

>> M
M =
         1           2           0           0           0
         3           5           6           0           0
         0           7           9          10           0
         0           0          11          13          14
         0           0           0          15          16

It works perfectly with any size matrices, e.g.:

C = {[1,2;3,4],[5,6;7,8],[1,2,3;4,5,6;7,8,9],[9,10;11,12],[13,14;15,16]};

gives

M =
         1           2           0           0           0           0           0
         3           5           6           0           0           0           0
         0           7           1           2           3           0           0
         0           0           4           5           6           0           0
         0           0           7           8           9          10           0
         0           0           0           0          11          13          14
         0           0           0           0           0          15          16

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mohammed hussein 2017-11-19

thank you very much for your answer , this is exactly what i want

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Answer 2

Walter Roberson 2017-11-18

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https://ww2.mathworks.cn/matlabcentral/answers/367853-replace-part-of-matrix-to-another-matrix#answer_291890

在 MATLAB Online 中打开

A=[1 2 ;3 4];
B=[5 6;7 8];
C=[9 10;11 12];
D=[13 14;15 16];
newvals = {A, B, C, D};
a = zeros(5,5);
for K = 1 : length(newvals)
  a(K:K+1, K:K+1) = newvals{K};
end

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mohammed hussein 2017-11-19

Thank you very much for your answer

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Answer 3

Andrei Bobrov 2017-11-18

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/367853-replace-part-of-matrix-to-another-matrix#answer_291908

编辑：Andrei Bobrov 2017-11-18

在 MATLAB Online 中打开

In your case (without loop)

k = cat(3,A,B,D,C);
[m,n,q] = size(k);
a = full(gallery('tridiag',q*m/2+1,1,1,1));
ii = ((1:m*n-1) + (0:q-1)'*m*n)';
a(a>0) = k([ii(:);prod([m,n,q])]);

in general case (with for..end loop)

C = {[1,2;3,4],[5,6;7,8],[1,2,3;4,5,6],[9,10;11,12],[13,14;15,16]};
[m,n] = cellfun(@(x)size(x),C(:));
s = sum(m-1) + 1;
a = zeros(s,sum(n-1)+1);
jj = 1;
for ii = 1:numel(m)
    id = jj + (0:m(ii)-1)' + s*(0:n(ii)-1);
    a(id) = C{ii};
    jj = id(end);
end