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Index a v dimensional matrix from a matrix with v columns and n rows

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Jpk
Jpk 2020-9-30
编辑： madhan ravi 2020-9-30
Hello all,
I a have u row and n column matrix, say p, in which I want to store some data. I also have a matrix ind which has per each row the indices that I need in order to write to.
For example let me se the dimension to n=2 and supposing I want to write to position ind(1,:) of P I have:
ind = [1,2;2,6];
p(sub2ind([size(p,1),size(p,2)],ind(1,1),ind(1,1))) = datum; % Ican easly loop to handle more data
While this works I am not clear how to address the possibililty of having a 50 column (i.e. n=50) ind matrix as the prototype of subs2ind requires me to specify the indexes on by one.
Does anyone know how to deal with such scenario?

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回答（1 个）

madhan ravi
madhan ravi 2020-9-30
p(sub2ind(size(p), ind(:, 1), ind(:, 2)) = Dayum % where RHS should be equal to size(ind)
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Jpk
Jpk 2020-9-30
编辑：Jpk 2020-9-30
You have to excuse me - I was not paying enough attention both in writing my question or in my reply. I will edit the question soon but allow me to reformulate.
Consider ind a t row and n column matrix of indices.
My goal is to use for each row of ind an index for a specific dimension of p. Of course n is know ahead of time.
eg.
ind = [1,2,4;2,6,5];
p( sub2ind(size(p),ind(1,1),ind(1,2),ind(1,3)) ) = datum; % in this case n=3
if n=4
ind = [1,2,4,5;2,6,5,9];
p( sub2ind(size(p),ind(1,1),ind(1,2),ind(1,3),ind(1,4)) ) = datum; % in this case n=4
In other words the kth colum of ind contains the indices for the kth dimension of p.
madhan ravi
madhan ravi 2020-9-30
编辑：madhan ravi 2020-9-30
for k = 1 : size(ind, 1)
I = num2cell(ind(k, :))
p(sub2ind(size(p), I{ : }))= datum;
end

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