Hello,
Thanks John and David. I ll look into your suggestions and I ll ensure I
post more details the next time.
Thanks,
Vyshnnavi
On Jul 7, 2015 8:19 AM, David L Carlson dcarl...@tamu.edu wrote:
As John suggests, more information and some sample data would help. I
haven't used loocv, but here is a simple example of leave one out cross
validation with simple linear regression. This does not eliminate the loop,
but uses lapply() which makes specifying the loop simpler. The results of
the 40 regressions are stored in a list called results and results.coef
contains the intercept and slope for each regression in a matrix.
set.seed(42)
x - rnorm(40, 10, 2)
y - x + rnorm(40, 0, 2)
results - lapply(1:40, function(i) lm(y[-i] ~ x[-i]))
results.coef - t(sapply(results, coef))
summary(results.coef)
(Intercept) x[-i]
Min. :-0.1477 Min. :0.8408
1st Qu.: 0.2032 1st Qu.:0.9830
Median : 0.2613 Median :0.9883
Mean : 0.2933 Mean :0.9866
3rd Qu.: 0.3240 3rd Qu.:0.9959
Max. : 1.9160 Max. :1.0245
-
David L Carlson
Department of Anthropology
Texas AM University
College Station, TX 77840-4352
-Original Message-
From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of John Kane
Sent: Monday, July 6, 2015 6:53 PM
To: Vyshnnavi Parthasarathy; r-help@r-project.org
Subject: Re: [R] Leave one out procedure - R
Hi Vyshnnavi,
I'd suggest having a look at
http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
and http://adv-r.had.co.nz/Reproducibility.html for some hints on how to
ask questions on the R-help List.
At the moment I don't think you have supplied enough information, code,
and data for people to easily answer your questions.
BTW if you are supplying sample data the best way is to use the dput()
function. It provides an exact copy of the data set that you are working
with.
Sorry not to be of any substantive help.
John Kane
Kingston ON Canada
-Original Message-
From: vyshnnavia...@gmail.com
Sent: Mon, 6 Jul 2015 08:56:52 -0700
To: r-help@r-project.org
Subject: [R] Leave one out procedure - R
Hello,
I am still in the process of familiarizing myself with R, pardon me if
this
is basic. I want to run a leave one out procedure for a 40 member
dataset.
At the moment I am doing it via a simple for loop. I wanted to know if
there is a superior way to do it. I read about the loocv command here -
http://artax.karlin.mff.cuni.cz/r-help/library/DMwR/html/loocv.html.
Since
I need to save the output generated in each iteration, I am not very sure
how exactly to implement the same using the loocv command. If you could
give me an insight into how to do it/ suggest quicker ways to do leave
one
out cross validation, it would be really helpful!
Thanks,
Vyshnnavi
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