[Rd] irrelevant warning message

[Gabor Grothendieck]

On Tue, Jan 13, 2009 at 8:28 AM, Terry Therneau <therneau at mayo.edu> wrote:
> Thanks for the replies:
>
> Duncan:
>> and got a warning in all R versions I tried back to 2.4.1.  In 2.3.1
>> this was an error.
>
>  It seems I have egg on my face wrt this point.  A more true synopsis of what I
> saw should have been that 1. I've never noticed this in R before and 2. Until
> recently I did all my modeling in Splus or Bell S, and character vectors always
> worked there.  (My survival routines were always more up to date in Splus
> because that's what I use for the source code.  But conversion from a local cvs
> archive to Rforge is nearly done -- just a survexp.us ratetable issue remains --
> so R will become my most current version in another day or two.)  Possibly I
> don't have any character variables as covariates in the survival test suite.
>
>
> Hadley:
>> I think R's handling of character vectors has progressed to the point
>> where they should be the norm, not the exception.  Maybe others will
>> have different views.
>
>  Factors are very useful when there is a small discrete number of levels, and I
> use them moderately often.  For that case, most of the default behavior of
> factors makes perfect sense, e.g., retention of levels.  I'm very sure that
> adding stringsAsFactors to the system options was a good thing, not as sure that
> defaulting it to FALSE is the best thing for all users.
>   In my world most of the data comes from formal processes: clinical trials,
> data bases, large studies that use dedicated keyed entry, etc.  The most common
> character variables are things like id, name, and address for which the factor
> paradym doesn't work, and most of the variables I get that are actually
> 'factors' come to me as small integers; I turn them into factors using both the
> levels and labels arguments.  Thus autoconversion is just a PITA. But my world
> is not everyone's.
>   My main complaint with factors has always been the assumption that everything
> should be turned into one.  I fought that battle with Splus.  Defaults behavior

See the stringsAsFactors option in ?options to change the global default.