[R] programming questions
ivo.welch at gmail.com
Wed Nov 3 19:17:39 CET 2010
yikes. this is all my fault. it was the first thing that I ever
defined when I started using R.
is.defined <- function(name) exists(as.character(substitute(name)))
I presume there is something much better...
On Wed, Nov 3, 2010 at 2:12 PM, Erik Iverson <eriki at ccbr.umn.edu> wrote:
> ivo welch wrote:
>> quick programming questions. I want to "turn on" more errors. there
>> are two traps I occasionally fall into.
>> * I wonder why R thinks that a variable is always defined in a data frame.
>> > is.defined(d)
>>  FALSE
>> > d= data.frame( x=1:5, y=1:5 )
>> > is.defined(d$z)
>>  TRUE
>> > is.defined(nonexisting$garbage)
>>  TRUE
> Which package/version of R is the 'is.defined' function in?
> I don't seem to have it here on 2.11.1, which I know is not
> the latest version of R.
> What does 'defined' mean?
>> this is a bit unfortunate for me, because subsequent errors become
>> less clear. right now, I need to do '(is.defined(d) and
>> !is.null(d$z))' to check that my function inputs are valid. It would
>> be nicer if one could just write "if (is.defined(d$z)".
> "z" %in% names(d) ?
>> * is there a way to turn off automatic recycling? I would rather get
>> an error than unexpected recycling. I can force recycling with rep()
>> when I need to.
>> Ivo Welch (ivo.welch at brown.edu, ivo.welch at gmail.com)
>> R-help at r-project.org mailing list
>> PLEASE do read the posting guide
>> and provide commented, minimal, self-contained, reproducible code.
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