To find the position of the elements which are same in vector

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UTA
UTA 2012-9-12
I have a vector like this: a = [ 2 3 4 2 5 4 3 3]; and I want to find all the index of the elements which has the same value. output like this: # 2, [1 4] # 3, [2 7 8] # 4, [3 6] # 5, [5]

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采纳的回答

Matt Fig
Matt Fig 2012-9-12
find(a==2)
  2 个评论
UTA
UTA 2012-9-12
but I have to search for a(1) to a(end), and that has duplicate ,how to simply this?
Matt Fig
Matt Fig 2012-9-12
编辑：Matt Fig 2012-9-12
Oh, well that's another thing.
a = [ 2 3 4 2 5 4 3 3];
[J,J] = histc(a,unique(a));
T = accumarray(J.',(1:length(J)).',[], @(x) {x});
Now T has the indices you seek.

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更多回答（2 个）

per isakson
per isakson 2012-9-12
编辑：per isakson 2012-9-12
Try
num = [ 2 3 4 2 5 4 3 3 ];
unq = unique( num );
ii = arrayfun( @(x) find( num==x ), unq, 'uni', false ) ;
>> unq
unq =
2 3 4 5
>> ii{:}
ans =
1 4
ans =
2 7 8
ans =
3 6
ans =
5
or use a for-loop
Javier
Javier 2013-8-28
编辑：Javier 2013-8-28
ind=unique(a)
for i = 1 : length(ind);
[z] =find(a==ind(i))
limit(i,:)=[z(1) z(end)]
end
out = [ind limit]
regards

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