MATLAB Answers

Count vector position in a matrix

5 views (last 30 days)
steve Brian
steve Brian on 9 Apr 2020
Commented: the cyclist on 10 Apr 2020
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!

  0 Comments

Sign in to comment.

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

steve Brian
steve Brian on 10 Apr 2020
This didn't work
edit: I solved. Thanks bro!!
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)

Tags

Community Treasure Hunt

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

Start Hunting!