CODEWITHSUNDEEP
arraysmatlab
user3473243
user3473243

Reputation: 65

Count and sum consecutive duplicate numbers

How to sum only consecutive duplicate numbers in order to find a unique value? for example, I have a vector 

A = [0 0 0 0 1 0 0 0 1 0 1 1 0 0 1 0 1]

then when summing only consecutive duplicate numbers, I will have 

B = [0 1 0 1 0 2 0 1 0 1]

finally the number of unique values different from 0 and 1 :

sum(B>1)

I know one way to solve the problem: 

sum(diff(find(A==1))==1)

but it seems it is not a good method.

Upvotes: 0

Views: 244

Answers (2)

karakfa
karakfa

Reputation: 67537

This will give you the total number of repeated values in the array including "0" values. 

sum(A(1:end-1)-A(2:end)==0)

ans =
 7

If you are interested only in the repeated "1" values, you can change it to

sum(A(1:end-1)+A(2:end)==2)

ans =
 1

Note that this is the count of duplicates if you have [1 1 1] you'll get 2 not 1.

Upvotes: 0

Robert Seifert
Robert Seifert

Reputation: 25232

An alternative solution:

A = [0 0 0 0 1 0 0 0 1 0 1 1 0 0 1 0 1]

%// get Islands
a = cumsum(~A)
b = a(logical(A))
%// count occurences 
c = histc(b,unique(b))
%// count number of occurences > 1 
d = sum(c > 1)
%// or sum of occurences > 1  
e = sum(c(c > 1))

c =
     1     1     2     1     1
d =
     1
e = 
     2

Upvotes: 1

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