Gad Abraham wrote:
> Hi,
>
> Design isn't strictly an R base package, but maybe someone can explain
> the following.
>
> When lrm is called within a function, it can't find the dataset dd:
>
> > library(Design)
> > age <- rnorm(30, 50, 10)
> > cholesterol <- rnorm(30, 200, 25)
> > ch <- cut2(cholesterol, g=5, levels.mean=TRUE)
> > fit <- function(ch, age)
> + {
> + d <- data.frame(ch, age)
> + dd <- datadist(d)
> + options(datadist="dd")
> + lrm(ch ~ age, data=d, x=TRUE, y=TRUE)
> + }
> > fit(ch, age)
> Error in Design(eval(m, sys.parent())) :
> dataset dd not found for options(datadist=)
>
> It works outside a function:
> > d <- data.frame(ch, age)
> > dd <- datadist(d)
> > options(datadist="dd")
> > l <- lrm(ch ~ age, data=d, x=TRUE, y=TRUE)
>
>
> Thanks,
> Gad
My guess is that you'll need to put dd in the global environment, not in
fit's environment. At any rate it is inefficient to call datadist every
time. Why not call it once for the whole data frame containing all the
predictors, at the top of the program?
Also it is inefficient to chop continuous variables. You can use the
proportional odds model with continuous ch as a response variable
although it will be slow if ch has more than, say, 100 unique values.
Frank
>
>
> > sessionInfo()
> R version 2.6.2 (2008-02-08)
> x86_64-pc-linux-gnu
>
> ...
>
> attached base packages:
> [1] splines stats graphics grDevices utils datasets methods
> [8] base
>
> other attached packages:
> [1] Design_2.1-1 survival_2.34 Hmisc_3.4-3
>
> loaded via a namespace (and not attached):
> [1] cluster_1.11.9 grid_2.6.2 lattice_0.17-4 rcompgen_0.1-17
>
--
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University
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