This function unfortunately does not work in 3d space. Thoughts?
On Wed, Aug 20, 2014 at 4:57 PM, Don McKenzie <d...@u.washington.edu> wrote: > ?dist > > from the help > > dist {stats} R Documentation > Distance Matrix Computation > > Description > > This function computes and returns the distance matrix computed by using > the specified distance measure to compute the distances between the rows of > a data matrix. > > Is this what you want? Computing on a matrix whose rows are your x, y, > and z values? > > > On Aug 20, 2014, at 1:12 PM, Patzelt, Edward <patz...@g.harvard.edu> > wrote: > > > R Community - > > > > I am attempting to write a function that will calculate the distance > > between points in 3 dimensional space for unique regions (e.g. localized > > brain regions such as the frontal lobe). > > > > For example I'm looking to compare each point in region 45 to every other > > region in 45 to establish if they are a distance of 8 or more apart. I > can > > do this linearly comparing each distance to the previous but this is not > > comparing all points. > > > > structure(list(Cluster.Index = c(46L, 46L, 46L, 46L, 46L, 45L, > > 45L, 45L, 45L, 45L, 44L, 44L, 44L, 44L, 44L, 43L, 43L, 43L, 43L, > > 43L), Value = c(8.21, 7.96, 7.85, 7.83, 7.8, 5.38, 4.56, 4.5, > > 4, 3.99, 5.42, 4.82, 4.21, 4.18, 3.91, 4.79, 4.27, 3.24, 3.06, > > 3.04), x = c(33L, 38L, 37L, 36L, 38L, 47L, 42L, 43L, 44L, 42L, > > 50L, 41L, 39L, 41L, 44L, 46L, 45L, 45L, 41L, 46L), y = c(15L, > > 12L, 12L, 13L, 13L, 91L, 84L, 84L, 95L, 96L, 69L, 70L, 65L, 65L, > > 59L, 41L, 40L, 46L, 44L, 47L), z = c(41L, 38L, 41L, 39L, 33L, > > 39L, 40L, 42L, 44L, 45L, 34L, 36L, 30L, 35L, 39L, 53L, 47L, 61L, > > 52L, 57L), X = c(NA, 6.557438524302, 3.16227766016838, 2.44948974278318, > > 6.32455532033676, 78.7464284904401, 8.66025403784439, 2.23606797749979, > > 11.2249721603218, 2.44948974278318, 30.2324329156619, 9.2736184954957, > > 8.06225774829855, 5.3851648071345, 7.81024967590665, 22.8910462845192, > > 6.16441400296898, 15.2315462117278, 10.0498756211209, 7.68114574786861 > > )), .Names = c("Cluster.Index", "Value", "x", "y", "z", "X"), row.names = > > c(NA, > > 20L), class = "data.frame") > > > > mainDat <- data.frame() > > for(i in 2:nrow(dat)){ > > tempDist <- (sqrt((dat$x[i] - dat$x[i-1])^2 + (dat$y[i] - dat$y[i-1])^2 + > > (dat$z[i] - dat$z[i-1])^2)) > > dat$X[i] <- c(tempDist) > > if(dat$Cluster.Index[i] != dat$Cluster.Index[i-1]){ > > mainDat <- rbind(mainDat, dat[i,]) > > } > > if((dat$Cluster.Index[i] == dat$Cluster.Index[i-1])) { > > if(tempDist > 8){ > > mainDat <- rbind(mainDat, dat[i,]) > > } > > } > > } > > > > > > > > > > -- > > > > *Edward H Patzelt | Clinical Science PhD StudentPsychology | Harvard > > University * > > > > [[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. > > Don McKenzie > Research Ecologist > Pacific Wildland Fire Sciences Lab > US Forest Service > > Affiliate Professor > School of Environmental and Forest Sciences > University of Washington > d...@uw.edu > > > > > -- *Edward H Patzelt | Clinical Science PhD StudentPsychology | Harvard University * [[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.