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...@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...@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. ______________________________________________ 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.