[Rd] variable scope in update(): bug or feature?
wuolong at gmail.com
Thu Dec 21 18:08:15 CET 2006
I stumbled upon this when using update() (specifically update.lm()). If
in the original call to lm(), say
a <- lm (y ~ x + z, data = mydata)
where y and z are in data frame mydata but x is in the global environment.
Then if later I run,
a0 <- update (a, ~ . - z)
a0$model will contain values of x in the global environment which may well
be different, even different length from mydata$y. Somehow, update() pads
a0$model to have the same number of rows as the length of x.
I would think that it would desirable to use x as in a$model rather than the
Is this a bug or a deliberate feature?
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