# How to count repeated rows of characters using a loop?

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Jason on 23 Mar 2014
Commented: Image Analyst on 23 Mar 2014
Say I have an array (I have already sorted alphabetically): results=[ABC;ABC;DEF;GHI;GHI;....]. I must use either a 'for' or 'while' loop (and I believe an 'if' statement will also make this easier) to find out how many times any repeated rows appear. i.e my above results would end up as [2;1;2;...]
thank you
Jason on 23 Mar 2014
I am GIVEN a CHAR matrix, all values already entered. To date all I have done is use "sortrows" to put the matrix in alphabetic order. My issue is coming to the loop, I have:
for 1:1:length(results)
if results(i,:)==results(i+1,:)
count= i+1
end
end
then matlab tells me "Index exceeds matrix dimensions"

Image Analyst on 23 Mar 2014
Hint: have you looked into sortrows() and unique()? If I were to do it for you, that's what I'd be looking up. Or maybe use hist(). Have you tried anything yet? Is this homework?
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Image Analyst on 23 Mar 2014
Jason, you should have tagged it as homework. Please do so now. OK, so you have a loop over rows - that should be obvious, right. Now what? How about having another loop inside over rows from 1 to the current row where you check the current row against all 3 column elements of all prior rows ? That seems to make sense. Now if a match is found, you'll need to increment something, and if no match is found, it's the first one found so far so you need to set the count array to 1 for that pattern. Just think it through and you'll get it. Come back with more code if you have trouble. We can't just hand over to you a turnkey solution.