Updating values in array based on index vector

Question

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Hi,

I have a 2D array (with zeros), and I want to update some indexes with 1's. I have a vectors with those indexes (seperatly for X and Y).

I can do a loop for i :Array(x(i),y(i)=1. but I'm looking for something more efficient (Run time is low, but probably I can do without loops)

Doing something like Array( X; Y ) = 1; is not doing what i'm looking for.

Any suggestions?

Thanks in advance :)

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Answer 1

Mohammad Sami 2020-5-28

1 个投票

One of the ways is to convert your subscript to linear index and then do the assignments.

ind = sub2ind(size(A),x,y);
A(ind) = 1;

Mohammad Sami 2020-5-28

A test case.

A = zeros(10,10);
x = 1:10;
y = 1:10;
ind = sub2ind(size(A),x,y);
A(ind) = 1; % set diagnol to 1

Felix 2020-5-28

sub2ind did the trick, Thanks!