Indexing and replacing value in a zero matrix based on a table

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I am trying to input a value in a zeros matrix of size 11*10. This is based on a variable which has three columns (Number, ID, ANS) as shown below. Now I want to insert the value in ANS which is -1 in the zeros matrix at 10x5 (ID x Number) position (index). Any suggestion on how this can be done?
Number ID ANS
5 10 -1

Accepted Answer

Walter Roberson
Walter Roberson on 19 Dec 2018
If your Number and ID and ANS are scalar then
YourMatrix(Number, ID) = ANS;
If they are vectors then there are multiple approaches, including:
YourMatrix( sub2ind(size(YourMatrix), Number(:), ID(:)) ) = ANS(:);
YourMatrix = YourMatrix + accumarray( Number(:), ID(:), ANS(:), size(YourMatrix) );
and there are approaches using sparse.

More Answers (1)

Arvind Sathyanarayanan
Arvind Sathyanarayanan on 19 Dec 2018
Is this what you're looking for?
ID = 10; Number = 5; Ans = -1;
tmat = zeros(11,10);


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