# Adding Number using for loop

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Tehreem Syed on 6 Aug 2020
Commented: Tehreem Syed on 6 Aug 2020
Hi,
I have 2 columns in data, time and s. I want to add all values of S when time = 1. Similarly, I want to repeat this for all values of time. I know this is a simple task, but i am not getting any output . Please help.

Benjamin Dassé on 6 Aug 2020
Hi,
When time = 1 you can sum all values of S in writing :
sum(S(time==1))
So you can do for all time values
Results = zeros(numel(unique(time)),2)
j=0;
for i = unique(time)'
j=j+1;
Results(j,:) = [i sum(Y(time==i))] % [new_time new_S]
end
Regards,

#### 1 Comment

Tehreem Syed on 6 Aug 2020
Thanks

KSSV on 6 Aug 2020
Let A be your n*2 array.
t = A(:,1) ;
s = A(:,2) ;
[C,ia,ib] = unique(t) ;
N = length(C) ;
iwant = zeros(N,1) ;
for i = 1:N
iwant(i) = sum(s(ib==i)) ;
end
iwant

Tehreem Syed on 6 Aug 2020
Tehreem Syed on 6 Aug 2020
I can accept only one answer, all of the solutions were really helpful and correct for me.
Regards