[R] The Claw Density and LOCFIT

Mark Difford mark_difford at yahoo.co.uk
Fri Jun 26 15:10:29 CEST 2009


Hi Jaap,

>> Could anybody please direct me in finding an updated version of this
>> document, or help me
>> correct the code given in the file. The (out-of-date) code is as follows:

You are not helping yourself, or anyone else, by not including the error
messages you get when trying to execute "your" code. The matter is in fact
quite straightfowards: ev does not accept an evaluation structure called
grid. The current documentation for locfit does tell you this: ?locfit.raw
(sub ev). When I executed your code I got

>   fit1 <- locfit( ~ claw54, deg = 0, kern = "gauss", alpha = c(0, 0.315),
> ev = 
+     grid(100, ll = -3.5, ur = 2.7)) 
Error in grid(100, ll = -3.5, ur = 2.7) : 
  unused argument(s) (ll = -3.5, ur = 2.7)

This explicitly tells you that the problem lies with the call to ev =
grid(...), which should in fact be ev = lfgrid(...). The following works for
me and should do so for you.

fit1 <- locfit( ~ claw54, deg = 0, kern = "gauss", alpha = c(0, 0.315), ev = 
       lfgrid(100, ll = -3.5, ur = 2.7)) 

HTH,
Mark.

R version 2.10.0 Under development (unstable) (2009-06-20 r48806) 
i386-pc-mingw32 

locale:
[1] LC_COLLATE=English_South Africa.1252  LC_CTYPE=English_South Africa.1252   
[3] LC_MONETARY=English_South Africa.1252 LC_NUMERIC=C                         
[5] LC_TIME=English_South Africa.1252    

attached base packages:
[1] splines   stats     graphics  grDevices utils     datasets  methods  
base     

other attached packages:
[1] locfit_1.5-4    lattice_0.17-25 akima_0.5-2     DPpackage_1.0-7
ade4_1.4-11     Design_2.2-0   
[7] survival_2.35-4 Hmisc_3.6-0    

loaded via a namespace (and not attached):
[1] cluster_1.12.0 grid_2.10.0    tools_2.10.0 


Van Wyk, Jaap wrote:
> 
> I am trying to reproduce Figure 10.5 of Loader's book: Local Regression
> and Likelihood. The code provided in the book does not seem to work.
> I have managed (a while ago) to get the accompanied R-code for the figures
> in the book (file called lffigs.R) from somewhere - cannot find it on the
> web anymore. The code in the .R script file does not work either.
> Could anybody please direct me in finding an updated version of this
> document, or help me correct the code given in the file. The (out-of-date)
> code is as follows:
> 
>    data(claw54)
>   fit1 <- locfit( ~ claw54, deg = 0, kern = "gauss", alpha = c(0, 0.315),
> ev =
>     grid(100, ll = -3.5, ur = 2.7))
>   fit2 <- locfit( ~ claw54, deg = 0, kern = "gauss", alpha = c(0, 0.985),
> ev =
>     grid(100, ll = -3.5, ur = 2.7))
>   x <- seq(-3.5, 2.7, length.out = 200)
>   y <- dnorm(x, -1., 0.1) + dnorm(x, -0.5, 0.1) + dnorm(x, 0, 0.1) +
> dnorm(x,
>     0.5, 0.1) + dnorm(x, 1., 0.1)
>   y <- (y + 5 * dnorm(x))/10
>   plot(fit1, get.data = T, main = "h=0.315", ylim = c(0, max(y)))
>   lines(x, y, lty = 2)
>   plot(fit2, get.data = T, main = "h=0.985", ylim = c(0, max(y)))
>   lines(x, y, lty = 2)
> 
> THANKS FOR ANY ASSISTANCE.
> ps: This code differs from that in the book. I have tried both, without
> success. Even if I just use, for example,
> fit1 <- locfit( ~ claw54, deg = 0, kern = "gauss", alpha = c(0, 0.315))
> I do not get the same result.
> 
> Jacob L van Wyk, Dept. of Statistics, University of Johannesburg (APK),
> Box 524, Auckland Park, 2006.
> Office: +27 11 559 3080, Fax: +27 11 559 2499
> 
> 
> ________________________________
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