[R] interpolation

[René Mayer]

Dear R-users,
I have a complex line by xy-values (ordered by z).
And I would like to get interpolated y-values on the positions of x = 0:600.
How do I get the correct points?

x=c(790,790,790,790,790,786,783,778,778,766,763,761,761,761,715,628,521,350,160,134,134,129,108,101,93,111,161,249,288,243,139,45,7)

y=c(606,606,606,606,606,612,617,627,627,640,641,641,641,641,689,772,877,1048,1240,1272,1272,1258,1242,1239,1239,1214,1122,959,770,479,273,133,45)

z=c(0,29,58,87,116,145,174,203,232,261,290,319,348,377,406,435,464,493,522,551,580,609,638,667,696,725,754,783,812,841,870,899,928)


plot(y,x,type="b")

# this fails ?????
lines(approx(y,x),col="blue") # with xout = c(0:600)

thanks in advance,
René



-- 
Dr. rer. nat. Dipl.-Psych. René Mayer

Dresden University of Technology
Department of Psychology
Zellescher Weg 17
D-01062 Dresden

Tel.: +49-351-4633-4568

Email: mayer at psychologie.tu-dresden.de