How to locate number from a matrix

I have matrix list2, it's a 526x2 double. Suppose the first column represents the ID of people, and the second column represents the total amount of films they shot. I want to find out the N most prolific films shot by the people. I used sort(list2(:,2),'descend') to rearrange the second colomn to get the most movie shot to the least. However, I also need to determine the people's ID, so the question is how to relocate back to the person's ID if we have the information of the second column?

Answer 1

[KSSV]

If idx is the indices of the locations in second column...to get the respective first column just use:

iwant = list2(idx,1)

[Kaijia Chen]

Thank you, but no.

idx is the indices of the second columns. I need to find the corresponding number of the first columns' number.

[KSSV]

Yes...that is what answer is for.

[Kaijia Chen]

Hi, I think I didn't explain my question clearly.

This is what i meant:

[Kaijia Chen]

So I rearrange the second column because I wanna find the people in descending order. The problem is how to relocate the first column in the same order? Thank you!

[KSSV]

A = rand(10,2) ; 
[val,idx] = sort(A(:,2)) ; 
iwant = A(idx,1)