replace part of matrix to another matrix
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mohammed hussein
on 18 Nov 2017
Commented: mohammed hussein
on 19 Nov 2017
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=
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
thank you very much for helping
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Accepted Answer
Stephen23
on 18 Nov 2017
Edited: Stephen23
on 18 Nov 2017
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
More Answers (2)
Walter Roberson
on 18 Nov 2017
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
Andrei Bobrov
on 18 Nov 2017
Edited: Andrei Bobrov
on 18 Nov 2017
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
All for MATLAB >= R2016b
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