Add element to the matrix in one sentence

I have a 2D matrix, say A=zeros(10,10). I want to add a vector of number to the matrix. I have the index of the elements, but it is repeated. E.g. the index [5,3,2,5,3,100,5] and the value is some random [1,2,3,4,5,6,7]. I then want to add 1 into 5th element of A, 2 into 3rd element and so on. How do I do this in one line?

[Adam]

Why do you need to do it in one line? Code doesn't cost money by the line!

[Xin]

Because I want to vectorize the whole code. Eventually A matrix is 1e7*1e7 and it is very slow if you do it in a loop

[Adam]

You can vectorize multi-line statements too.

[Xin]

Could you please be more specific. That's what I have been doing but for this problem it is not very straightforward.

Answer 1

[Andrei Bobrov]

A=zeros(10,10);
ii = [5,3,2,5,3,100,5];
var = 1:7;

[ii,ib] = unique(ii);
A(ii) = var(ib);

or

A([5,3,2,5,3,100,5]) = 1:7

[Xin]

The only problem is that if you do that, you only save the last entry into A. That means A(1)=7 but I want to add 1 and 7 into A(1)

[Andrei Bobrov]

This is not possible for a double array if only for cell array.

[Andrei Bobrov]

ii = [5,3,2,5,3,100,5];
var = 1:7;

A = reshape(accumarray(ii(:),var(:),[100 1],@(x){x(:)'}),10,[]);

Answer 2

[Guillaume]

If I understood correctly

A = zeros(10,10);
indices = [5,3,2,5,3,100,5];
values = [1,2,3,4,5,6,7];

A = A + reshape(accumarray(indices(:), values(:), [numel(A), 1]), size(A))

would be one way to do it. Alternatively,

 [uindices, ~, loc] = unique(indices);
 sumvalues = accumarray(loc(:), values(:));
 A(uindices) = A(uindices) + sumvalues;