I'm trying to sum every two row and store the answer in new matrix, but the code keep giving me the wrong sum and copy the wrong answer in all the row of the new matrix.

the code I'm talking about is cyrcled in red

Answer 1

[William Rose]

@ibrahim nathem,

Agg_load_1=10*rand(8,1);
N=length(Agg_load_1);
s=zeros(floor(N/2),1); %allocate array for the sums of 2 elements at a time
for i=1:length(s)
    s(i)=sum(Agg_load_1(2*i-1:2*i));
end
disp(Agg_load_1')

    5.2044    8.8178    8.3728    4.5701    3.4480    4.6383    4.2776    3.3500

disp(s')

   14.0222   12.9429    8.0862    7.6275

Try the above.

[William Rose]

@ibrahim nathem, If Agg_load_1 has an odd number of elements, the code above works without error. It rounds down when it allocates vector s. So if Agg_load_1 has 9 elements, s will have 4 elements and will not include a sum for Agg_load_1(9).

Answer 2

[William Rose]

@ibrahim nathem,

Agg_load_1=10*rand(8,1);
N=length(Agg_load_1);
s=Agg_load_1(1:2:end-1)+Agg_load_1(2:2:end);
disp(Agg_load_1'); disp(s')

The approach above is nicer than my first answer, because it does not use a for loop. It works when Agg_load_1 has an even number of elements. It would need an adjustment if Agg_load_1 has an odd number of elements.

[ibrahim nathem]

what should i change if i want to sum every 1440 row and have the final matrix (s) equal to (365,1). The file Agg_Load_1 has 525600 rows and 1 colum which is even number of rows

[Torsten]

S = arrayfun(@(i)sum(Agg_load_1((i-1)*1440+1:i*1440,:),'All'),1:525600/1440)

[William Rose]

@Torsten, nice!