zhijie zhang wrote:
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
In the former you select all elements of the vectors except the first or
last one, respectively.
In the next call you select just one arguemnt of each vector, namely the
first or last one.
Uwe Ligges
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 <lig...@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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