[R] Kernel density

[Christian Hennig]

Hi,

I want to fit a kernel density estimator by bkde of library KernSmooth.
I need only the density value at the point 0. 
I do not understand the following behaviour:

> q <- rnorm(100) 
> bkq <- bkde(q, bandwidth=0.11, gridsize=1, range.x=c(0,0))
Error in 0:L : NA/NaN argument
> bkq <- bkde(q, bandwidth=0.11, gridsize=1, range.x=c(-1,1))
> bkq
$x
[1] -1

$y
[1] NA

> bkq <- bkde(q, bandwidth=0.11, gridsize=3, range.x=c(-1,1))
Warning message: 
longer object length
	is not a multiple of shorter object length in: kappa * gcounts 
> bkq
$x
[1] -1  0  1

$y
[1] NA NA NA

> bkq <- bkde(q, bandwidth=0.11, range.x=c(-1,1))
(works, I get 401 proper y-values)

Adding truncate=FALSE does not change anything.
Do I really need to generate 401 (default gridsize) y-fits to extract the
one value I am interested in? What's the problem with specifying gridsize?

Best,
Christian


-- 
***********************************************************************
Christian Hennig
Seminar fuer Statistik, ETH-Zentrum (LEO), CH-8092 Zuerich (currently)
and Fachbereich Mathematik-SPST/ZMS, Universitaet Hamburg
hennig at stat.math.ethz.ch, http://stat.ethz.ch/~hennig/
hennig at math.uni-hamburg.de, http://www.math.uni-hamburg.de/home/hennig/
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