Subject: Re: [R] 'fixing' list components
From: Thomas Lumley (thomas@biostat.washington.edu)
Date: Thu 21 Sep 2000 - 03:28:58 EST
Message-ID: <Pine.GSO.4.21.0009201013420.10332-100000@atlas.biostat.washington.edu>
On Wed, 20 Sep 2000, Griffith Feeney wrote:
> I have a list x (say) that will contain many inputs to and outputs a model.
>
> x$input1 <- assign.input1(parameter1, parameter2)
>
> is one way to assign input1, but it would be neater to be able to do
>
> assign.input1(x, parameter1, parameter2)
>
> Is this a good idea? If so, what is a good way to do it?
No.
You can do it using assign() or eval() in the parent frame, but
a) this is often a sign that what you're doing is a bad idea
b) the syntax suggests that something like
assign.input1(foo(y),parameter1,parameter2)
should work, but it won't.
c) the code will just be a complicated and fragile way of constructing
the command
x<-assign.input(parameter1,parameter2)
anyway
d) It will be particularly tricky since the assign() function, the
obvious way of doing it, doesn't handle things like "x$input1" the way you
would expect.
-thomas
Thomas Lumley
Assistant Professor, Biostatistics
University of Washington, Seattle
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