Re: [R] Breakpoint in logistic GLM with 'segmented' package - error: replacement length zero

2012-05-25 Thread Vito Muggeo (UniPa)

dear Peter,
Your code appears correct, so it is difficult to reply without the data..

If you are interested in further details, please contact me off-list

vito


Il 25/05/2012 15.34, Peter Hoitinga ha scritto:

Hello all,

I've been having trouble with assessing a breakpoint in a logistic GLM
with two explanatory variables. For this analysis I've been using the
'segmented' package version 0.2-9.1. But I keep getting an error and I
don't see where I would be going awry. The situation is the following:

Two explanatory variables:
bedekking - a variable with possible values between 0 and 1 - mine
runs from 0.05 to 0.5, increasing with steps of 0.05
s.size - a count variable - increases from 3 to 25 with steps of 1,
and from 25 to 60 with steps of 5

Each combination of s.size and bedekking has 100 repeats so the
resulting dataframe 'dat.al2' consists of 3 observations of 3
variables.

Because the response variable has values between 0 and 1, I used a logistic GLM:


gmodel<- glm(R.AUC ~ bedekking + s.size, data=dat.al2, family = 
quasibinomial(link=logit))


R.AUC increases with increasing s.size and decreasing bedekking,
looking at the graph shows that the association reaches a plateau at a
s.size of 10 and a bedekking of 0.45. So these are the values I use in
'psi' argument in the 'segmented' function


psi.mod<- list(0.45, 10)
names(psi.mod)<- c("bedekking", "s.size")


Then I attempt to run the 'segmented' function:


seg.gm<- segmented(obj = gmodel, seg.Z= ~bedekking + s.size, psi = psi.mod)


When I run this, after half a minute I get the following error:

Error in ifelse(is.list(o0), o0$dev.no.gap, 10^12) :
   replacement has length zero

Does anybody know what might be causing this error, and could somebody
point out where I might go wrong?

Thanks in advance,

Peter

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--

Vito M.R. Muggeo
Dip.to Sc Statist e Matem `Vianelli'
Università di Palermo
viale delle Scienze, edificio 13
90128 Palermo - ITALY
tel: 091 23895240
fax: 091 485726
http://dssm.unipa.it/vmuggeo

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[R] Breakpoint in logistic GLM with 'segmented' package - error: replacement length zero

2012-05-25 Thread Peter Hoitinga
Hello all,

I've been having trouble with assessing a breakpoint in a logistic GLM
with two explanatory variables. For this analysis I've been using the
'segmented' package version 0.2-9.1. But I keep getting an error and I
don't see where I would be going awry. The situation is the following:

Two explanatory variables:
bedekking - a variable with possible values between 0 and 1 - mine
runs from 0.05 to 0.5, increasing with steps of 0.05
s.size - a count variable - increases from 3 to 25 with steps of 1,
and from 25 to 60 with steps of 5

Each combination of s.size and bedekking has 100 repeats so the
resulting dataframe 'dat.al2' consists of 3 observations of 3
variables.

Because the response variable has values between 0 and 1, I used a logistic GLM:

> gmodel <- glm(R.AUC ~ bedekking + s.size, data=dat.al2, family = 
> quasibinomial(link=logit))

R.AUC increases with increasing s.size and decreasing bedekking,
looking at the graph shows that the association reaches a plateau at a
s.size of 10 and a bedekking of 0.45. So these are the values I use in
'psi' argument in the 'segmented' function

> psi.mod <- list(0.45, 10)
> names(psi.mod) <- c("bedekking", "s.size")

Then I attempt to run the 'segmented' function:

> seg.gm <- segmented(obj = gmodel, seg.Z= ~bedekking + s.size, psi = psi.mod)

When I run this, after half a minute I get the following error:

Error in ifelse(is.list(o0), o0$dev.no.gap, 10^12) :
  replacement has length zero

Does anybody know what might be causing this error, and could somebody
point out where I might go wrong?

Thanks in advance,

Peter

__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.