[R] Use of variables to reference to objects

Thomas Lumley tlumley at u.washington.edu
Fri Nov 22 18:56:44 CET 2002

On Fri, 22 Nov 2002, Kris Nackaerts wrote:

> Hi,
> I'm new to R and looking for a way to use a variable to reference to an
> object.
> I'm plotting several graphs on top of each other and want to do this by
> a for loop. The field I want to graph have names like a1,a2,a3, ...
> I can't figure out how to get this working:
> It should look like this:
> lines(spectral$Wavelength,paste("spectral$a",j,sep=""),col=j)
> but the "paste()" does not seem to work in this context.

No, it wouldn't.  That gives you the name of the variable, not the

Probably the simplest solution is either
   lines(spectral$Wavelength, spectral[[paste("a",j,sep="")]],col=j)
but there's also
and various others


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