How to replace the elements of a Matrix with the elements of a vector

11 views (last 30 days)
Good evening, I must perform this task. I will post the code, I hope it is explicative, because it would be a hell of a matter to explain it with my own words:
close all
clear all
clc
A = [1, 2, 4, 7, 11, 16, 22, 29, 37, 46];
delta = A(2:end)-A(1:end-1);
delta(length(delta)+1) = min(delta);
% for those wondering: delta becomes delta = [1 2 3 4 5 6 7 8 9 1]; last element is because I need a tenth element (same size as A) and so I chose the lowest one.
matrice = [0 1 0 1 1 0 0 1 1 1; 1 0 0 0 1 1 1 0 1 1];
[row, col] = find(matrice);
matrice(row, col) = delta(col);
risultato = [0 2 0 4 5 0 0 8 9 1; 1 0 0 0 5 6 7 0 9 1]; % this is what I want the code to do, just don't consider it as a part of the code
So, with this code pasted, I can explain: I want that, while scanning the rows, the matrix element becomes the element in the correspondant column of delta. You find 1 in matrice(1,2) and you replace it with delta(2), for instance.
I will need that to perform the sum along the rows.
The issue is: referring to my example, I want to say "take matrice(1,2) and replace it with delta(2)". MATLAB doesn't speak my language and doesn't read me in my mind (of course, it's a program mounted on something which is wires and binary logic, stupid me! :D), and he understands that I want something else which he can't do. He tells me:
Unable to perform assignment because the size of the left side is 12-by-12 and the size of the right side is 1-by-12.
Error in Sandbox (line 121)
matrice(row, col) = delta(col);
Why don't my good friend MATLAB and I understand each other? What can I do to come an agreement with it? :D
Thanks for your suggestion and I hope that I sound fun enough while you're reading this.
Just two things:
  • don't suggest me solutions where a for-loop is used because who's evaluating my job is very, very annoying. This stuff is going to be inside a for-loop and whenever that person sees a nested for, that person gets a mortal panic attack. I don't want dead people on my heart. Second, the code actually gets slower.
  • I'm using MATLAB r2020, but that person loves old stuff. So I need a solution compatible with r2009 (such a pain in the arse)

Accepted Answer

Sibi
Sibi on 1 Dec 2020
Edited: Sibi on 1 Dec 2020
A = [1, 2, 4, 7, 11, 16, 22, 29, 37, 46];
delta = A(2:end)-A(1:end-1);
delta(length(delta)+1) = min(delta);
matrice = [0 1 0 1 1 0 0 1 1 1; 1 0 0 0 1 1 1 0 1 1];
output=delta.*(matrice)
  2 Comments

Sign in to comment.

More Answers (0)

Community Treasure Hunt

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

Start Hunting!

Translated by