[R] Extract the names of the arguments in an "expression"

[Gabor Grothendieck]

2011/3/24 Javier López-de-Lacalle <javier.lopezdelacalle at ehu.es>:
> Hi everybody:
>
> I need to get the names of the arguments in an object of class "expression".
> I've got the following expression:
>
>> x <- expression(rho * cos(omega))
>
> Is there any function or procedure that returns the names of the arguments
> (in the example: "rho" and "omega")?
>

Try this:

> all.vars(x)
[1] "rho"   "omega"

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