# How to count repeated number pairs in matlab?

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Ram k on 5 May 2016
Commented: Image Analyst on 5 May 2016
Suppose I have a sequence 5,5,5,1,5,4,1,2,3,5,5,1,5 then 5 followed by 5 is 3 so answer is 3, so how to programme it in Matlab.

CS Researcher on 5 May 2016
Edited: CS Researcher on 5 May 2016
Lets assume the vector is a, i.e.,
a = [5,5,5,1,5,4,1,2,3,5,5,1,5];
Try this:
numberOfPairs = sum(numel(find(diff(a)==0)));
Hope this helps!
Ram k on 5 May 2016
I want to obtain transition probability matrix by this sequence in that I want calculate probability matrix by equation as follows probability= (number of pairs one state followed by other)/(number of pairs first state followed by any another state), how to do this.

Image Analyst on 5 May 2016
You can find out how many pairs of all integers are next to all other integers with the gray level cooccurrence matrix, given by graycomatrix() if you have the Image Processing Toolbox
m = [5,5,5,1,5,4,1,2,3,5,5,1,5]
glcm = graycomatrix(m, 'NumLevels', max(m),'GrayLimits',[])
glcm =
0 1 0 0 2
0 0 1 0 0
0 0 0 0 1
1 0 0 0 0
2 0 0 1 3
For example, 5 is next to 5 3 times. 5 is next to 1 two times. 3 is next to 2 two times, etc.
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Image Analyst on 5 May 2016
To get "(number of pairs one state followed by other)" - read it from the GLCM array. To get "(number of pairs first state followed by any another state)" just count up the total number of that number as long as that number is not in the last row or last column
subArray = fullMatrix(1:end-1, 1:end-1);
numAnyPairs = sum(subArray(:));

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