Alternative to 'find' which won't return multiple values?

Hello,

I am running the following code, which works most of the time but occasionally causes issues. The problem is that ocassionally the values in 'topfit' will have more than 1 match in the matrix 'totalsale', so the 'position' variable is not a constant size. Due to the nature of the rest of the code it is imperative position be just 10 figures.

I have tried just limiting position to 10 figures manually by setting position = position(1:10,:) but that has it's own problems.

position = find(ismember(totalsale,topfit)); %check the numbers in topfit that match totalsale
topstack = finalpop(position,:);

finalpop is a 100x16 matrix.

Totalsale is a 100x1 matrix of the fitness values of the rows in finalpop.

Topfit is a 10x1 matrix, the top 10 totalsale fitness values, in descending order.

Can anyone recommend a way to return only the 10 rows in finalpop which produced the top 10 fitness values? Could I assign each a number 1-10 and somehow assign that to finalpop to find them? Stuck for ideas. Thanks!

For reference:

If the fitness values produced were : 100,99,98,97,96,95,94,93,92,91,91,91,91

I would like to return the finalpop values that produced the first 10 and ignore the other three 91 values, even though they are just as fit.

Answer 1

[dpb]

If you're using R2017b or later...

[~,i10mx]=maxk(topfit,10);           % return 10 largest positions in topfit vector
topstack = finalpop(i10mx,:);        % look up those in the array

NB: Unless there's other need for it, there's no reason to make a separate variable topfit just for the winners--just refernce the proper column index of the overall array.

[dpb]

Oh, now I see Steven beat me to it... :)

[Stephen]

This did the trick! Thank you!

Answer 2

[Steven Lord]

The find function allows you to request the first N or the last N non-zero elements of the input array. Those are maximum limits; if you ask it to return the first 5 non-zero elements of an array that only has 3 non-zero elements, you're only going to get those three.

But since you mentioned looking for some maximum values, the maxk function may also be of interest to you.