arrowFactor.R
arrowColors<- function(v, colors) {
n <- length(v); k <- length(colors)
midPoints <- (v[-1] + v[-n])/2
colors[cut(midPoints, k)]
}
arrowColors<- function(v, colors) {
n <- length(v); k <- length(colors)
midPoints <- (v[-1] + v[-n])/2
colors[cut(midPoints, k)]
}