[R] Join points with arrows based a TIME variable

[Uwe Ligges]

zhijie zhang wrote:
> Hi,
>  I have a data set with three variables,X Y and Time. X and Y are the
> coordinates of points, i want to join these points according to the Time
> sequence using arrows?
> Demo Example data:
>> x<-c(1:6)
>> y<-c(1:6)
>> time<-c(6:1)
>> data<-cbind(x,y,time)
>> data
>      x y time
> [1,] 1 1    6
> [2,] 2 2    5
> [3,] 3 3    4
> [4,] 4 4    3
> [5,] 5 5    2
> [6,] 6 6    1
>   I hope to join the six points with points' time=1 as starting point and
> points' time=6 as endpoint. So the sequence is time=1,2,3,4,5,6 and join the
> corresponding points with arrows.
>   Any ideas on it?


data <- data.frame(data[order(data[,"time"]),])
with(data, plot(y ~ x))
with(data, arrows(x[-length(x)], y[-length(x)], x[-1], y[-1]))


Uwe Ligges


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