R help - Mar 2009 - Partial sum of a vector

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
	[[alternative HTML version deleted]]

Dear Mohammad,
Take a look at the rollmean function in the zoo package.

HTH,

Jorge

On Sun, Mar 1, 2009 at 9:29 PM, Mohammad Sabr
<mohammad_sabr@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
>        [[alternative HTML version deleted]]
>
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>
	[[alternative HTML version deleted]]

?filter
> x
 [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19
20
> filter(x, rep(1,4))
Time Series:
Start = 1
End = 20
Frequency = 1
 [1] NA 10 14 18 22 26 30 34 38 42 46 50 54 58 62 66 70 74 NA NA


On Sun, Mar 1, 2009 at 9:29 PM, Mohammad Sabr <mohammad_sabr 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
> ? ? ? ?[[alternative HTML version deleted]]
>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

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
> ? ? ? ? [[alternative HTML version deleted]]
>
> ______________________________________________
> R-h... at r-project.org mailing
listhttps://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.