Look at the CRAN Task View: "Handling and Analyzing Spatio-Temporal Data," particularly the section on "Moving objects, trajectories." The tools you need are probably already available.
https://cran.r-project.org/web/views/SpatioTemporal.html ------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Sidoti, Salvatore A. Sent: Thursday, December 17, 2015 3:25 PM To: r-help@r-project.org Subject: [R] Converting from Continuous 2D Points to Continuous 2D Vectors 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.
