And an alternative to nested if else's, in a case where they are
actually needed, is
switch
-Don
At 1:06 PM -0400 8/25/09, Ista Zahn wrote:
Nice one Gabor! It works great, and is really simple. Bill Dunlap's
solution of
GET$pass.var <- as.name(GET$pass.var)
eval(substitute(mean(x), list(x=GET$pass.var)))
also works.
Thanks!
On Tue, Aug 25, 2009 at 12:59 PM, Gabor
Grothendieck<ggrothendi...@gmail.com> wrote:
Try this:
x <- get(GET$pass.var)
mean(x)
On Tue, Aug 25, 2009 at 12:26 PM, Ista
Zahn<iz...@psych.rochester.edu> wrote:
Hi everyone,
I'm building a website (http://*yourpsyche.org) using Jeffrey Horner's
awesome Rapache module. I want to take user input, and pass it to an R
script. At first I was simply using if else statements, but after a
while I had so many nested if else's in my code that my head was
spinning. So then I started using cat() and source() to write
temporary files and read them back in (see example below). I've
searched around, and I think there might be a better way to do it with
substitute(), but I can't seem to figure it out (see attempt below).
Here is a minimal example:
###set up simple example###
GET <- list(pass.var="b")
a <- 1:10
b <- 11:20
###using if else works but becomes confusing when I have a lot
of variables to pass###
if(GET$pass.var=="a")
+ {
+ mean(a)
+ } else if(GET$pass.var=="b")
+ {
+ mean(b)
+ }
[1] 15.5
###writing to a temporary file works but feels like a hack and
results in many temp
>> files###
>>> cat('print(mean(', GET$pass.var,'))', file="tmp.R",sep="")
>>> source("tmp.R")
>> [1] 15.5
>>>
>>> ###this seems promising but I can't figure it out###
>>> substitute(mean(x), list(x=GET$pass.var))
mean("b")
###is there a better way?###
Thanks!
--
Ista Zahn
Graduate student
University of Rochester
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--
Ista Zahn
Graduate student
University of Rochester
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://*www.*R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
