Here is a dodge I often use. This is a mock-up example.
_______________
bar <- data.frame(matrix(rnorm(1001), nrow = 1))
names(bar)[1] <- "y" ## say
head(bar[,1:5])
nbar <- names(bar)
form <- as.formula(paste(nbar[1], "~", paste(nbar[-1], collapse = "+")))
fitModel <- substitute(tm <- rpart(FORM, data = DATA),
list(FORM = form, DATA = quote(bar)))
fitModel ## the screen quietly erupts...
library(rpart)
eval(fitModel) ## to do the job.
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The advantage of proceeding this way is that the object you create, fm, has a
meaningful (but large!) formula in it and the name of the dataframe from which
the variables come. This makes it easy, e.g. to use manipulation tools on it.
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of James Hirschorn
Sent: Sunday, 24 October 2010 11:51 AM
To: r-help@r-project.org
Subject: [R] Long model formulae
What is a good way to enter a very long model formula. For example:
y ~ Input.2 + Input.3 + ... + Input.1000
(assuming the corresponding dataframe has many other columns).
Is there a way to convert a character string to a formula? Are there command
line expansions in R besides the simple '.'?
Thanks.
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
