How to rank a vector with repeats without MATLAB unique?
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Hi everybody,
I need to rank a vector and currently i'm using this two commands:
data_s=sort(data); [~,rank]=ismember(data,data_s);
For a vector data=[1 1 1 2 2 2 3 3 3] i get i=[1 1 1 4 4 4 7 7 7], but instead i would like to get i=[1 1 1 2 2 2 3 3 3], without using MATLAB function 'unique'. Anybody has any suggestion?
Thanks in advance.
3 Comments
Guillaume
on 27 Jun 2016
"without using MATLAB function unique" Why?
It's possible to get the same output as unique using any of the set functions ismember, setdiff, union, etc., because internally they all call unique. But in that case, why not call unique directly?
If the reason is because it's an assignment, then using any of these functions just to avoid unique is probably not going to earn you a good mark. I would think that you'd be expected to come up with your own unique algorithm.
Answers (2)
Jan Orwat
on 27 Jun 2016
Do you want to replicate following behaviour?
[~, ~, rank] = unique(data);
rank = rank.';
There are thousands of ways to do that. For example:
[foo, bar] = sort(data);
rank(bar) = cumsum([1, diff(foo)~=0]);
But, as the cyclist wrote, are you sure?
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