eval and as.name
Murray Cooper wrote:
I am new to R, so maybe I'm missing the point of your question. But why wouldn't you just use sum(a,b)?
if you know you want to sum a and b, sure you would. if you need to sum
the variables named by the components of some dynamic character vector,
you need to lookup ('dereference') the names in some way.
vQ
Murray M Cooper, Ph.D. Richland Statistics 9800 N 24th St Richland, MI, USA 49083 Mail: richstat at earthlink.net ----- Original Message ----- From: "Fuchs Ira" <irafuchs at gmail.com> To: <r-help at r-project.org> Sent: Thursday, February 05, 2009 5:10 PM Subject: [R] eval and as.name
I'm sure there is a more general way to ask this question but how do
you use the elements of a character vector as names of objects in an
expression?
For example, say you have:
a = c(1,3,5,7)
b = c(2,4,6,8)
n=c("a","b")
and you want to use the names a and b in a function (e.g. sum)
sum(eval(as.name(n[1])),eval(as.name(n[2])))
works but
what is a simpler way to effect this level of indirection?
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______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.