Re: [R] list of variables of an expression

From: David Winsemius <dwinsemius_at_comcast.net>
Date: Tue, 15 Jun 2010 18:07:46 -0400

On Jun 15, 2010, at 5:45 PM, Alberto Lusiani wrote:

> I would like to get the list of variables of an expression: is that
> possible? I searched the help and the web without success. In
> practice, given an expression like
>
> expr = parse(text="x^2+y^3")
>
> I would like to have a function such as:
>
> vars(expr)
>
> returns
>
> c("x", "y") or a list like the one returned by formals().

attr(terms(formula(paste("~", "x^2+y^3"))), "variables") # returns list(x, y)

>
> Regards,
> --
> Alberto
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT



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