[R] update() a LME-with correlated errors object

[Christian Salas]

Hi there

I cannot update a fitted LME-with spatially correlated errors object, 
please check the example. Data from an R book, only 281 rows, the 
provided code download the data from my website.

I use R 2.8.1 under linux-ubuntu, For this session i was using the 
following packages
     Package Version
1      nlme  3.1-90
2  datasets   2.8.1
3      MASS  7.2-46
4     utils   2.8.1
5     stats   2.8.1
6  graphics   2.8.1
7 grDevices   2.8.1
8   methods   2.8.1
9      base   2.8.1


The code!!

# Fitting a LME with correlated errors
# Example and data from Book: Bivand et al 2008 "Applied spatial
# data analysis with R"
###################################################

#example--------------------------------
#1. read data
#data from the book, i built the .csv file
dbase <- 
read.csv(url("http://environment.yale.edu/salas/data/spatDataBivandetal08.csv"),
  header = TRUE)

head(dbase)
dim(dbase)

#fit a linear model (just for fun)
nylm <- lm(Z~PEXPOSURE+PCTAGE65P+PCTOWNHOME, data=dbase)
summary(nylm)

#fit a mixed-effect model [p.288 of Bivand et al] with correlated
# errros depending on the distance between the centroids of the areas
library(nlme)

#specify correlation structure [also explained in Pinheiro&Bates, p.238]
sp1 <- corSpatial(1, form = ~ x + y, type = "gaussian")
scor<-Initialize(sp1, dbase[,c("x", "y")], nugget=FALSE)

#fit the LME with correlated errors
spmodel<-lme(Z~PEXPOSURE+PCTAGE65P+PCTOWNHOME,
              random=~1|AREAKEY,
              data=dbase, correlation=scor, method="ML")

summary(spmodel)

#the problem------------
#I want to fit the same mixed-effect model with correlated structure
# for a different havin n-i observations and of course the same columns
dbnew=dbase[-1,]
nrow(dbnew) #one less observation than before

#here is the error, or bug?
update(spmodel, data=dbnew) #here is the error!!!!!, why?
#after running this, appear a large message, summarized here
#
#*** glibc detected *** /usr/lib/R/bin/exec/R: free(): invalid next size 
(normal): 0x0950f090 ***
#======= Backtrace: =========
#/lib/tls/i686/cmov/libc.so.6[0xb7b6e454]
#/lib/tls/i686/cmov/libc.so.6(cfree+0x96)[0xb7b704b6]
#b6ddb000-b6ddc000 r--p 00633000 08:05 1574
#Process R aborted at Mon Apr  6 09:12:41 2009

#I did also check this in a Windows OS, and I obtained the same problem.
#I did also check with an older version of nlme, and I obtained the same 
#problem.


any suggestion?

thanks in advance


-- 
-------------------------------------------------------------------------------
Christian Salas                     E-mail:christian.salas at yale.edu
PhD candidate                       http://environment.yale.edu/salas
School of Forestry and Environmental Studies
Yale University                     Tel: +1-(203)-432 5126
360 Prospect St                     Fax:+1-(203)-432 3809
New Haven, CT 06511-2189            Office: Room 35, Marsh Hall
USA

Yale Biometrics Lab                  http://environment.yale.edu/biometrics