How to assign values to a sparse matrix without iterations?

Hi, All,

I want to assign non-zero values to a matrix H. I know the locations of all the non-zeros. For example, I know the non-zero locations:

It indicates H(1,1)=1;H(1,2)=1;H(2,1)=1;H(2,5)=1;H(3,2)=1;H(3,3)=1;...

Would you please tell me how I can quickly assign this values without iterations?

Thanks a lot. Bei

Answer 1

[Adam]

i = repmat( 1:size( Nonloc ), [1 2] );
j = Nonloc(:)

s = sparse( i, j, 1 );

[Benson Gou]

Dear Adam,

Thanks a lot for your excellent code. It works very well.

Best regards, Bei

Answer 2

[dpb]

S=sparse(Nonloc(:,1),Nonloc(:,2),1);

[Benson Gou]

Dear dpb,

I tried your code, but it is not correct. Please check yourself.

Thanks a lot. Bei

[dpb]

Well, I guess that depends on what is "correct". It sets the index values in the Nonloc array to 1 for each i,j pair by row (what I intended and inferred was what Nonloc was representing).

I see looking at the example you've got some other arrangement listed; I don't follow what the logic is that selected those locations???

[Bruno Luong]

The logic is adam code:

• i is the number of rows of NonLoc,
• j are 2 values of the row #i of NonLoc.

[dpb]

If you say so...I still don't see it, but I guess if he does that's all that matters.

[Benson Gou]

Hi, dab and Bruno,

Thanks for your comments. I think dab's code gives one "1" in each row while Adam gives two "1" in each row which is expected.

Thanks a lot again. Bei

[dpb]

Ah! The light finally dawneth...the row isn't given but implied.