# How to get the starting and ending index of repeated numbers in an array?

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yashvin on 22 Jun 2015
Commented: yashvin on 26 Jun 2015
Hi MY array is =[2 2 1 2 3 2 2 2 2 2 3 5 6 7 7 7 7 6 5]
I am trying to find the starting and index index of repeated numbers in my array
for example,
for number 2, i expect startingindex=1 and endingindex=2 as it is repeated and also startingindex=6th and endingindex=10.
for number 7, i expect startingindex=14 and endingindex=17
I have been trying using find so far but in vain

Jan on 22 Jun 2015
An another question from the forum concerning a run-length-encoding. With FEX: RunLength:
X = [2 2 1 2 3 2 2 2 2 2 3 5 6 7 7 7 7 6 5];
[B, N, Ind] = RunLength(X);
Ind = [Ind, length(X)+1];
Multiple = find(N > 1);
Start = Ind(Multiple);
Stop = Ind(Multiple + 1) - 1;
yashvin on 23 Jun 2015
Thanks!! works perfectly

Ingrid on 22 Jun 2015
try using the diff function before calling find
yashvin on 26 Jun 2015
Let me check it and get back to you. Thanks for your input

Andrei Bobrov on 22 Jun 2015
Edited: Andrei Bobrov on 22 Jun 2015
A=[2 2 1 2 3 2 2 2 2 2 3 5 6 7 7 7 7 6 5];
ii = [0, diff(A(:)')==0,0];
i1 = strfind(ii,[0 1]);
i2 = strfind(ii,[1 0]);
out = [A(i1)',i1(:),i2(:)];
##### 2 CommentsShowHide 1 older comment
yashvin on 26 Jun 2015
@ Andrei Bobrov
But i am new to strfind. According to
It looks for pattern and the example in the page treats pattern in string mostly. Can you please a little description of the code you had written. Thanks!

Azzi Abdelmalek on 22 Jun 2015
Edited: Azzi Abdelmalek on 22 Jun 2015
A=[2 2 1 2 3 2 2 2 2 2 3 5 6 7 7 7 7 6 5];
d1=~diff(A).*(1:numel(A)-1);
idx1=d1.*[1 ~d1(1:end-1)];
idx2=circshift(d1.*[~d1(2:end) 1],[0 1]);
ii1=~~idx1;
out=[A(ii1);idx1(ii1) ;idx2(~~idx2)+1];

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