Re: [R] Referencing to an object within a function

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Tue, 19 Feb 2008 14:36:21 -0500

On 2/19/2008 2:22 PM, Benjamin Zuckerberg wrote:
>
> I am encountering an error when I attempt to reference a glm model
> within a function. The function uses the segmented.glm command
> (package = segmented). Within the segmented.glm command one specifies
> an object, in this case a logistic regression model, and specifies a
> starting threshold term (psi). I believe this is an environment
> problem, but I do not have a solution. Any assistance would be
> greatly appreciated. The function is as follows:
>

>> colonization <- function(x,y){


> library(segmented)


> 	col <- subset(final,final[,x] == 2 | final[,x] == 4)

> 	col[,x] <- ifelse(col[,x] == 2,1,0)

> 	glm1 <- glm(col[,x]~col[,"PLAND"],family=binomial)

> 	glm2 <- segmented.glm(obj = glm1, seg.Z = ~PLAND, psi=y, it.max = 100)

> }

>> colonization("PIWO",48)

>
> Error in eval(expr, envir, enclos) : object "x" not found

You could use traceback() to find the location of the error, but I would suspect it's a bug in segmented.glm. You should contact the maintainer of that package (Vito Muggeo) to work it out. (I've cc'd him.)

Duncan Murdoch

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