Hi Gudmund,
Let's call the matrix, M. Let's find all the entries in column 2, corresponding to the value of 1 in column 1. You can use logical indexing ( to do that as illustrated below:
>> M(M(:,1)==1,2)
ans =
132
8989
The above command gives you all the entries in the second column corresponding to an entry of 1 in the first. Hence, you can pass the output as an argument to the "sum" command,
>> sum(M(M(:,1)==1,2))
ans =
9121
If you want to repeat this for all the values in Var1(i.e. 1,2 and 3) then you can make use of MATLAB for-loop like this:
for i = 1:3
sum1(i,1) = sum(M(M(:,1)==i,2));
end
Refer to the following documentation for logical indexing:
I hope this helps!
Thanks,
Tushar
