Ok. And what is the problem now? B.
On Dec 17, 2015, at 4:25 PM, Sidoti, Salvatore A. <sidoti...@buckeyemail.osu.edu> wrote: > Greetings! > > I have a fairly large dataframe (df) with pathing information in the form of > continuous x,y coordinates: > > df$x > df$y > > With these data, I would like to: > 1. Calculate a set of continuous vectors > 2. Determine the angle between each of these vectors (in degrees) > 3. Count the number of angles in the dataframe that meet a certain threshold > (i.e. <90°) > > Here's what I've come up with so far: > > ### Function that calculates the angle between two vectors in 2D space: > > angle <- function(x,y){ # x and y are vectors > dot.prod <- x%*%y > norm.x <- norm(x,type="2") > norm.y <- norm(y,type="2") > theta <- acos(dot.prod / (norm.x * norm.y)) > (180*as.numeric(theta))/pi # returns the angle in degrees > } > > ### Test the function: > x <- as.matrix(c(2,1)) > y <- as.matrix(c(1,2)) > angle(t(x),y) > [1] 36.8699 > > Thank you! > ______________________________________________ > 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. ______________________________________________ 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.