[R] Plot Arrows with Angle and length

[S Ellison]

> The arrows command uses the start and end coordinates of each vector, but
> I have the starting coordinates, azimuth, and length.
> 
> So, There are package that plot this arrows?
> 
> Example:
> 
> > x<- c(1,2,4)
> > y<- c(2,3,5)
> > Azimuth<- c(45,90,180)
> > Length<- c(1,0.5,1)

May be packages out there but if it's a quick fix you want, roll your own.

arrows.az <- function(x, y, azimuth, length, ..., units=c("degrees", "radians")) {
	units <- match.arg(units)
	az.rad <- switch(units,
		degrees=azimuth*pi/180,
		radians=azimuth
	)
	arrows(x, y, x+cos(az.rad)*length, y+sin(az.rad)*length, ...)
}

plot(0:6, 0:6, type="n")
arrows.az(x, y, Azimuth, Length)

"..." means you can pass all the other options to arrows()

S Ellison


> 
> 
> Thanks,
> 
> Julio
> 
> 	[[alternative HTML version deleted]]
> 
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