Join points with arrows based a TIME variable

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?

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Hi Uwe,
  It works. Why does the following argument generate different results?
with(data, arrows(x[-length(x)], y[-length(x)], x[-1], y[-1]))
#correct,multiple joins

with(data, arrows(x[1], y[1], x[length(x)], y[length(x)]))  #wrong,seems to
be only one join
  From the ?arrows, the second argument should work. What is the problem?
  Thanks a lot.
#codes:
x<-c(1:6);y<-c(1:6);time<-c(6:1);data<-cbind(x,y,time);data
data<-data.frame(data[order(data[,"time"]),])
with(data, plot(x,y))
with(data, arrows(x[-length(x)], y[-length(x)], x[-1], y[-1]))

with(data, plot(x,y))
with(data, arrows(x[1], y[1], x[length(x)], y[length(x)]))
2009/11/4 Uwe Ligges <ligges at statistik.tu-dortmund.de>

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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