# Find highest third of values in dateset?

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Peter Mills on 12 Jan 2018
Edited: Star Strider on 12 Jan 2018
WaveHeight=[3 1 5 2 3.1 6 5.5 3 2.5];
We need to find the highest 1/3:
HighestThird=[6 5.5 5]
But what if we what a function that will calculate the mean of the heights 1/3 of WaveHeight with the length of WaveHeight being a variable which may be large?
E.g.
WaveHeight=randi(1000,1,1000);
HighestThird=
Edited: Adam on 12 Jan 2018
"calculate the mean of the heights 1/3 of WaveHeight"
I don't understand what this means. What is it you want to take the mean of and what is it you want 1/3 of?
Since you are starting your own question here it makes sense to include your information here rather than reference a comment in another question with more information than this one. There is no guarantee that independent question (or the answer to which you replied) will not get deleted.

Star Strider on 12 Jan 2018
Edited: Star Strider on 12 Jan 2018
One approach is to use the sort function:
WaveHeight=[3 1 5 2 3.1 6 5.5 3 2.5];
[Waves,Idx] = sort(WaveHeight, 'descend');
HighestThird = WaveHeight(Idx(1:fix(numel(Idx)/3)))
HighestThird =
6 5.5 5
also:
HighestThird = Waves(1:fix(numel(Idx)/3))
with the same result.