Extract speed and direction from x,y-coordinates

xy_speed_pos.R

# dataframe 'dat' w/ x,y-coords in columns 'x' and 'y' and timestamp in column, 'ts', e.g.:
library(soccermatics)
attach(tromso)
dat <- subset(tromso, id == 8)[,c(1,3:4)]

#calculate direction of each vector angle (in radians)
v <- diff(complex(real = dat$x, imaginary = dat$y))
dat$direction <- c(NA, diff(Arg(v)) %% (2*pi), NA) - pi

# calculate speed (distance / time interval)
dist <- c(NA, Mod(v))
dat$speed <- abs(dist / c(NA, difftime(dat$ts[-nrow(dat)], dat$ts[-1])))

# example plot
soccerFlow(dat, 10)