R help - Apr 2002 - Linear extrapolation; revision to earlier posting

The S-Plus approx function implements rule=3 (linear extrapolation), which is
not implemented in R.  Has anyone extended approx to handle linear
extrapolation?

Regarding the use of approx for "closest matching" in my post from
last week, you need to add ties=function(x)x[1], e.g.

round(approx(c(1,3,5,2,4,2,4),1:7,xout=c(1,3,5,2,4,2,4),rule=2,
       ties=function(x)x[1])$y)

-- 
Frank E Harrell Jr              Prof. of Biostatistics & Statistics
Div. of Biostatistics & Epidem. Dept. of Health Evaluation Sciences
U. Virginia School of Medicine  http://hesweb1.med.virginia.edu/biostat
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