How to add values from vector

Hello all,

Suppose I have a vector and I want to add every five sequential values together. So for example if v1=[1 1 1 1 1 1 1 1 1 1]; Then I'm expecting to get v2 as: v2=[5 5]; How to implement this in matlab?

I tried the following code:

%%%%%%%

v=[1 1 1 1 1 1 1 1 1 1];

for i=1:i+5:length(v)

   v2(i)=v(i)+v(i+1)+v(i+2)+v(i+3)+v(i+4)

end

%%%%%%%

But the answer was wrong; it was

v2=[5 0 0 0 0 5]

Answer 1

[per isakson]

A Matlabish way

    >> sum( reshape( ones(1,10), 5, [] ) )
    ans =
         5     5

it assumes that the length of v1 is a multiple of 5

[Nourhan]

What if the length is not multiples of 5? How can I add zeros?

[Sagar Damle]

I have used the answer given by per isakson to solve your problem.Try it!

v = [1 1 1 1 1 1 1];
leng = length(v);
x = mod(leng,5);
if x ~= 0
    v(leng+1 : leng+(5-x)) = 0;
end  

sum( reshape( v, 5, [] ) )

[per isakson]

Yes, pad with zeros is a good idea.

    >> v1 = ones( 1, 17 );
    >> v1 = cat( 2, v1, zeros( 1, (5-rem(length(v1),5) ) ) );
    >> length( v1 )
    ans =
        20

One-liners is a Matlab sport. However, this one-liner adds an extra five zeros to v1 when length already is a multiple of five (appropriate smiley).

One more try

    v1 = cat( 2, v1, zeros( 1, rem((5-rem(length(v1),5)),5) ) );

There is always another edge-case that will error.