On Sep 30, 2011, at 10:14 AM, Duncan Murdoch wrote:
On 30/09/2011 10:00 AM, David Winsemius wrote:
On Sep 30, 2011, at 4:50 AM, sreblam wrote:
> Hi!
> I'm trying to implement in R in an easy way the negative
reflection
> method
> described in Silverman (1986) on p.31, ie I have a non-negative
> dataset and
> would like to estimate the density by applying a reflection method
> where the
> reflected points have weight -1.
> I thought there should be a way to evaluate the wanted kernel at
the
> required points, in other words to calculate formula (2.16):
> fhat(x) = 1/(nh) * sum_{i=1}^{n}{ K( (x-Xi) /h) - K( (x-Xi) /h) }
>
> Unfortunately, I am still not that good and skilled with R - does
> anybody
> know how to do this- Or maybe a hint...?
> Thank you!!
Doing what I thought was the obvious search ( "negative reflection
density" ) done at the obvious search site (the one to which
RSiteSearch("negative reflection density") ) typed at the console
would have taken you) and twiddling with the setting produces this
perfect match as its second hit:
http://finzi.psych.upenn.edu/Rhelp10/2010-July/246526.html
That's a reflection density estimate, but not a "negative
reflection" estimate. The latter aims for zero density at location
0, not zero gradient to the density there.
PLease ignore my first response. I see that the problem is not solved
as easily as I fantasied. The logspline package is given by otehrs in
the same thread as offering a mechanism for setting boundaries on
densities.
--
David.
Duncan Murdoch
Now it is true that you wouldn't have gotten that with the console
entered string which is why I created a new function (and a new
browser button that fiddles with the default setting for RSiteSearch:
rhelpSearch<- function(string,
restrict = c("Rhelp10", "Rhelp08", "Rhelp02",
"functions" ),
matchesPerPage = 100, ...)
RSiteSearch(string=string, restrict = restrict,
matchesPerPage = matchesPerPage, ...)
R-search button mapped to:
http://search.r-project.org/cgi-bin/namazu.cgi?query=&max=100&result=normal&sort=score&idxname=Rhelp10&idxname=Rhelp08&idxname=Rhelp02&idxname=functions
>
> PS: you can also find the mentioned passage on p.21 of
> http://ned.ipac.caltech.edu/level5/March02/Silverman/paper.pdf
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/Implementing-Silverman-s-Negative-Reflection-tp3859191p3859191.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
