On Mar 23, 2012, at 1:53 PM, heyi xiao wrote:
Sarah,
Thanks for the response. I actually have several years of working
experience with R and statistics, although may not be as good as
you. that’s why I am here ;) I dug deeper into R documentations and
previous R-help posts, and couldn’t found anything particular help.
Again, I want to do two things: (1) estimate the probability density
of this bivariate distribution using some nonparametric method
(kernel, spline etc);
?MASS::kde2d
?KernSmooth::bkde2D
?ade4::s.kde2d
help(package=locfit)
(2) sample a big dataset from this bivariate distribution for a
simulation study.
What is wrong with `sample`?
# to get sample of size n without replacement
set.seed(42)
dfrm[ sample(1:NROW(dfrm), n) , ]
--
David.
If my questions are not clear enough show my how I can improve, or
which part is not clear enough. If you have any particular
suggestions/comments, you are more than welcome. Thanks!
Heyi
--- On Fri, 3/23/12, Sarah Goslee <sarah.gos...@gmail.com> wrote:
From: Sarah Goslee <sarah.gos...@gmail.com>
Subject: Re: [R] Nonparametric bivariate distribution estimation
and sampling
To: "heyi xiao" <xiaohey...@yahoo.com>
Cc: r-help@r-project.org
Date: Friday, March 23, 2012, 12:26 PM
R can do all of that and more.
But you'll need to put some work in reading about how to use
R, about
the statistical methods involved, and about how to use them
to best
effect. You might want, for instance, generalized additive
models. Or
not. If your question isn't more fully-formed than this,
your best bet
is almost certainly to talk to a local statistician, spend
some time
working with R, and then come back to the list with
specific
questions.
Sarah
On Fri, Mar 23, 2012 at 12:17 PM, heyi xiao <xiaohey...@yahoo.com>
wrote:
Dear all,
I have a bivariate dataset from a preliminary study. I
want to do two things: (1) estimate the probability density
of this bivariate distribution using some nonparametric
method (kernel, spline etc); (2) sample a big dataset from
this bivariate distribution for a simulation study.
Is there any good method or package I can use in R for
my work? I don’t want parametric models like bivariate
normal distribution etc, as I would like to accurate model
my data. I don’t want to use the bootstrapping approach,
i.e. sampling with replacement, as this will generate lots
of duplicate data points. Any thoughts or input will be
highly appreciated!
Heyi
--
Sarah Goslee
http://www.functionaldiversity.org
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David Winsemius, MD
West Hartford, CT
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