On Mar 23, 2015, at 3:44 AM, <lluis.hurt...@uv.es> <lluis.hurt...@uv.es> wrote:
> Dear all, > > I am currently working with the spatstat package with 3D samples. I am trying > to > evaluate a non analytical function over the window that encloses the sample > and I > need to know which is the fastest way of doing it. > > The function input is a 3 coordinate position in the window (x,y,z) and a > list of > parameters (a,b,c). The output is a numerical value. > > n <- function(x,y,z,a,b,c) Perhaps: dfrm <- as.data.frame.table(your_volume_matrix) n.out <- with(dfrm, mapply( n, x=x, y=y, z=z, MoreArgs=list(a=a,b=b,c=c) ) _ dim(n.out) <- dim(your_volume_matrix) You don't describe the form of this "3 coordinate position in the window (x,y,z)" so perhaps the arguments will need to be extracted. I took a WAG at one approach. If it's not in long-form, you need configure the array indices for either a volume or surface into a dataframe, perhaps with `expand.grid` or `as.data.frame.table`. You also don't describe the sort of integration you imagine. Why not a simple sum of that result divided by the volume? I cannot imagine any faster procedure. > But I need to do it over the whole volume. > > For 2 dimensions it can be done with > > A <- as.im(function,window,parameters) > norm <- integral.im(A) > > For 3 dimensions I have tried to pass an array of a grid covering the window > (like a > quadrature scheme) and then summing up the output array, but I would like to > know if > there is any faster way of integrating the function. > > Thank you very much, > > Lluís Hurtado > IFCA > www.ifca.unican.es > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
