[R] Partial sum of a vector

[andrew]

perhaps this?

M <- dim(data_m)[2]

for(j in 1:M){
    for (i in 4:T) {
        data_q[i-3,j]=sum(data_m[(i-3):i,j])
    }
}

of course, you can vectorize this and speed it up significantly, but
there is something evil about premature optimization.

On Mar 2, 1:29 pm, Mohammad Sabr <mohammad_s... at yahoo.com> wrote:
> I am trying to run a loop where I can sum parts of a matrix. For example, I want at each step in the loop to sum the the next 4-values of a vector. I tried to do the following but the result were wrong:
>  
> for (i in 4:T) {
> data_q[i-3,]=sum(data_m[i-3,]:data_m[i,])}
>
>  
> can anyone please direct me on what should I do to run this loop properly
>  
> Thanks in advance
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>
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