Creating new vector that only has duplicates from original vector.

I need help with a small part of my code.

r1=randi(6,1,5)
rollnumber=0;
        if Y==0 && rollnumber<2
        rollnumber=rollnumber+1;
        uniquer1=unique(r1)
        countOfr1=hist(r1,uniquer1)
        indexToRepeatedValue = (countOfr1~=1)
        repeatedValues=uniquer1(indexToRepeatedValue)
        numberOfAppearancesOfRepeatedValues=countOfr1(indexToRepeatedValue);
        r1repeated=repeatedValues
        r1numberofrepeated=numberOfAppearancesOfRepeatedValues

    r1repeated=repeatedValues %this gives me the value of the repeated numbers

    r1numberofrepeated=numberOfAppearancesOfRepeatedValues %this gives me how many times each number is repeated

Both of these are useful but I need a new vector that just has the repeated values.

The problem is I cannot figure out how to create a new vector with just the repeated values.

Example

r1=randi(6,1,5)
r1=[1 1 4 5 5] %values of r1
r2=[1 1 5 5] %the new r2 vector I need

I have read through my book and searched online and I have not been able to figure this out.

Thank you.

[Stephen23]

Please do not edit your question and remove the text. This is very rude.

http://www.mathworks.com/matlabcentral/answers/16153-is-deleting-threads-helpful-in-this-forum

[Rena Berman]

(Answers dev) Restored question.

Answer 1

[Thorsten]

 [ur1 a b] = unique(r1);
 r2 = r1(ismember(r1, ur1(find(histc(b, unique(b)) == 2))));

[Thorsten]

I see. Please use

[ur1 a b] = unique(r1);
r2 = r1(ismember(r1, ur1(find(histc(b, unique(b)) > 1))));

And if you need it sorted, add

r2 = sort(r2);

[Thorsten]

 r5 = [r4(r4 == r3(1)) r3];