bug (PR#13570)

Berwin A Turlach wrote:

G'day Peter,

On Thu, 05 Mar 2009 09:09:27 +0100
Peter Dalgaard <p.dalgaard at biostat.ku.dk> wrote:

rhafen at stat.purdue.edu wrote:

<<insert bug report here>>

This is a CRITICAL bug!!!  I have verified it in R 2.8.1 for mac
and for windows.  The problem is with loess degree=0 smoothing.
For example, try the following:

x <- 1:100
y <- rnorm(100)
plot(x, y)
lines(predict(loess(y ~ x, degree=0, span=0.5)))

This is obviously wrong.

Obvious? How? I don't see anything particularly odd (on Linux).

Neither did I on linux; but the OP mentioned mac and windows. 

On windows, on running that code, the lines() command added a lot of
vertical lines; most spanning the complete window but some only part.  

Executing the code a second time (or in steps) gave sensible
results.  

My guess would be that some memory is not correctly allocated or
initialised.  Or is it something like an object with storage mode
"integer" being passed to a double?  But then, why doesn't it show on
linux?

Happy bug hunting.  If my guess is correct, then I have no idea how to
track down such things under windows.....

Cheers,

	Berwin

Please can you folks try under R-devel (to be R-2.9.0 in a couple of 
weeks) and report if you still see it. I do not under R-devel (but do 
under R-release), so my guess is that something called by loess() has 
been fixed in the meantime.

Moreover it is not the plot stuff that was wrong under R-2.8.1 (release) 
but the loess computations.

Uwe Ligges

Hi Uwe,

This is not a problem under Vista, using "a" development version (mine now
somewhat outdated).

Regards, Mark.

sessionInfo()
R version 2.9.0 Under development (unstable) (2009-01-22 r47686) 
i386-pc-mingw32 

locale:
LC_COLLATE=English_South Africa.1252;LC_CTYPE=English_South
Africa.1252;LC_MONETARY=English_South
Africa.1252;LC_NUMERIC=C;LC_TIME=English_South Africa.1252

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

other attached packages:
[1] ade4_1.4-10     Design_2.1-2    survival_2.34-1 Hmisc_3.5-2    

loaded via a namespace (and not attached):
[1] cluster_1.11.12    gamlss_1.9-4       grid_2.9.0         lattice_0.17-20   
latticeExtra_0.5-4
[6] MASS_7.2-45        tools_2.9.0 


Uwe Ligges-3 wrote:

Berwin A Turlach wrote:

G'day Peter,

On Thu, 05 Mar 2009 09:09:27 +0100
Peter Dalgaard <p.dalgaard at biostat.ku.dk> wrote:

rhafen at stat.purdue.edu wrote:

<<insert bug report here>>

This is a CRITICAL bug!!!  I have verified it in R 2.8.1 for mac
and for windows.  The problem is with loess degree=0 smoothing.
For example, try the following:

x <- 1:100
y <- rnorm(100)
plot(x, y)
lines(predict(loess(y ~ x, degree=0, span=0.5)))

This is obviously wrong.

Obvious? How? I don't see anything particularly odd (on Linux).

Neither did I on linux; but the OP mentioned mac and windows. 

On windows, on running that code, the lines() command added a lot of
vertical lines; most spanning the complete window but some only part.  

Executing the code a second time (or in steps) gave sensible
results.  

My guess would be that some memory is not correctly allocated or
initialised.  Or is it something like an object with storage mode
"integer" being passed to a double?  But then, why doesn't it show on
linux?

Happy bug hunting.  If my guess is correct, then I have no idea how to
track down such things under windows.....

Cheers,

	Berwin

Please can you folks try under R-devel (to be R-2.9.0 in a couple of 
weeks) and report if you still see it. I do not under R-devel (but do 
under R-release), so my guess is that something called by loess() has 
been fixed in the meantime.

Moreover it is not the plot stuff that was wrong under R-2.8.1 (release) 
but the loess computations.

Uwe Ligges