maxk from subset of array

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Orr Streicher
Orr Streicher on 17 Aug 2021
Commented: Yazan on 17 Aug 2021
I would like to solve the following prblem:
Lets say i have the vector :v=[10,22,3,-5,8,6,100,30,12,9]
I want to find the indicies and the values of the k largest number from a given subset, e.g: if the indices of the subset are [1,3,5,8] and k=2 the function will return: values=[10,30], indices=[1,8].
There is any suggestion how to implemet it?

Accepted Answer

Yazan on 17 Aug 2021
clc, clear
v = [10,22,3,-5,8,6,100,30,12,9];
subIdx = [1,3,5,8];
k = 2;
% sort values and get corresponding indices
[val, idx] = sort(v(subIdx), 'descend');
% get only k values
val = val(1:k);
% get actual indices
Idx = subIdx(idx(1:k));
val = 1×2
30 10
Idx = 1×2
8 1
Yazan on 17 Aug 2021
You may also use Matlab native function maxk instead of sorting the values. This might save you some processing power.

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