Count vector position in a matrix

2 views (last 30 days)
Hi all. I need an algorithm, which takes my first element (! = 0) from an array and checks that element in a vector that already contains the elements of the matrix (! = 0) and begins to count the position it is in. Once it has found the respective element, it adds its position in another vector.
Ex: I have A = [ 2 3 4 0;
8 7 0 0;
2 0 1 3]
VectorA= [ 2 3 4 8 7 2 1 3] (elements != 0)
rowptr = [1 4 6]
Explain:
2 is in position 1 in the vectorA -> rowptr = [ 1
8 is in position 4 in the vectorA -> rowptr = [ 1 4
2 is in position 6 -> rowptr = [1 4 6]
A little help, please!

Accepted Answer

the cyclist
the cyclist on 9 Apr 2020
Here's one way:
tmp = cumsum(sum(A~=0,2))
rowptr = [1; tmp(1:end-1)+1];
  2 Comments
the cyclist
the cyclist on 10 Apr 2020
Hm. I believe it worked on your example.
I'd be curious to see an example where this algorithm does not work, and your solution.
Maybe you should post your own code as a solution, and accept it, rather than accepting my incorrect solution.

Sign in to comment.

More Answers (0)

Categories

Find more on Dialog Boxes in Help Center and File Exchange

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by