[R] update.formula has 512 char buffer?

[Duncan Murdoch]

On 12-02-28 2:11 PM, Chris Hane wrote:
> Hello,
>
> I am trying to "paste" together a formula to use in the mob function of
> party. This means the formula will be of the form y ~ x1+ ...+xM | z1+..zN.
>
> I am doing some preliminary fits of y ~ x1+ ...+xM, then want to add the
> conditional part of the equation using update().
>
> Here's the test code:
> var1<- 1:78
> x1<- paste("x", var1, sep="")
> f1<- paste("f", var1[1:10], sep="")
>
> # use first 77 variables
> fmla<- as.formula( paste("y ~ ", paste(x1[1:77], collapse=" + ", sep=""),
> sep=""))
> fmla2<- update(fmla, paste(". ~ . | ", paste(f1, collapse= " + "), sep=""))
>
> # CHANGE x to all 78 variables
> fmla<- as.formula( paste("y ~ ", paste(x1, collapse=" + ", sep=""),
> sep=""))
> fmla2<- update(fmla, paste(". ~ . | ", paste(f1, collapse= " + "), sep=""))
>
> I have run this in Windows and Linux (64 bit) and both fail when using all
> 78 terms (and anything more than 78 terms). The error message contains
> Error in parse(text = x) : :1:514: unexpected ')'.
>
> Changing the length of the names of the x variables will break the update()
> with fewer variables, but always with an error referring to just more than
> 512 characters.  There is nothing special about 77 or 78 variables here; I
> want to do this with hundreds of variables.
>
> Is there a workaround to this?

I've just committed code to R-devel (to become 2.15.0 at the end of the 
month) to remove the truncation.  I don't know any workaround that will 
address this in earlier versions, other than "don't use very long formulas".

It also affects as.character() applied to a formula object, and some 
other cases where very long language objects are displayed.

Please test R-devel or one of the alpha/beta versions once they are 
built; this fix went into revision 58544.

Duncan Murdoch

>
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