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

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;

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Azzi Abdelmalek 2015-6-22

As indicated in the above answer, you can get RunLength function in this link http://www.mathworks.com/matlabcentral/fileexchange/41813-runlength

yashvin 2015-6-23

Thanks!! works perfectly

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Answer 2

Ingrid 2015-6-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/224769-how-to-get-the-starting-and-ending-index-of-repeated-numbers-in-an-array#answer_183502

try using the diff function before calling find

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Stephen23 2015-6-22

编辑：Stephen23 2015-6-22

在 MATLAB Online 中打开

@yashvin: notice that Ingrid mentioned two functions: diff and find. You only tried the first function, but you missed the find.

>> V = [2 2 1 2 3 2 2 2 2 2 3 5 6 7 7 7 7 6 5];
>> X = diff(V)~=0;
>> B = find([true,X]) % begin of each group
B =
     1     3     4     5     6    11    12    13    14    18    19
>> E = find([X,true]) % end of each group
E =
     2     3     4     5    10    11    12    13    17    18    19
>> D = 1+E-B % the length of each group
D =
     2     1     1     1     5     1     1     1     4     1     1

Use logical indexing if you only want the groups with more than one element:

>> Y = D>1;
>> B(Y)
ans =
     1     6    14
>> E(Y)
ans =
     2    10    17

yashvin 2015-6-26

Let me check it and get back to you. Thanks for your input

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Answer 3

Andrei Bobrov 2015-6-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/224769-how-to-get-the-starting-and-ending-index-of-repeated-numbers-in-an-array#answer_183503

编辑：Andrei Bobrov 2015-6-22

在 MATLAB Online 中打开

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(:)];

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yashvin 2015-6-26

I tried your solution. It is working perfectly so far.

yashvin 2015-6-26

@ Andrei Bobrov

But i am new to strfind. According to

http://www.mathworks.com/help/matlab/ref/strfind.html

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!

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Answer 4

Azzi Abdelmalek 2015-6-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/224769-how-to-get-the-starting-and-ending-index-of-repeated-numbers-in-an-array#answer_183535

编辑：Azzi Abdelmalek 2015-6-22

在 MATLAB Online 中打开

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];