Complete matrix with vectors as indices in matlab

Question

Let us say that we have a matrix A1 and two vectors v1 and v2 as follow:

A1=zeros(5, 5);
v1=[1 2 3];
v2=[5 5 4];

Is there a way to replace the

Answer 1

Convert your vectors into linear indices:

A1=zeros(5, 5);
v1=[1 2 3];
v2=[5 5 4];

ind=sub2ind(size(A1), v1, v2);
A1(ind(1))=1

A1 =

     0     0     0     0     1
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0

etc.

Answer 2

Basically you have row and column information and need to convert them into a linear index, to index into A1. For this, use sub2ind -

A1(sub2ind(size(A1),v1(1),v2(1))) = 12
A1(sub2ind(size(A1),v1(2),v2(2))) = 10
A1(sub2ind(size(A1),v1(3),v2(3))) = 9

Output -

A1 =

     0     0     0     0    12
     0     0     0     0    10
     0     0     0     9     0
     0     0     0     0     0
     0     0     0     0     0

If you have those values stored in some array, array1, use this for the same result as above -

array1 = [12 10 9];
A1(sub2ind(size(A1),v1,v2)) = array1;