Re: [Rd] Table vs unique

From: Göran Broström <gb_at_stat.umu.se>
Date: Thu, 22 Jul 2010 22:54:21 +0200

On 07/21/2010 03:54 PM, Prof Brian Ripley wrote:
> I believe this is a misdiagnosis: the 'rounding' is done by
> as.character (as the help for argument 'levels' in ?factor does say)

> and ?as.character has a full explanation (and is linked from the
> relevant part of ?factor).
>
> as.numeric(as.character()) should do the trick.

Or

temp <- signif(temp, digits = 15)

which seems to be much faster.

Göran B.

>
> On Wed, 21 Jul 2010, Terry Therneau wrote:
>
>> A bug in the survival routines was reported to me today. The root cause
>> is a difference between table, unique, and sort.
>>
>>> temp<- rep(c(1, sqrt(2)^2, 2), 1:3)
>>> unique(temp)
>> [1] 1 2 2
>>> table(temp)
>> temp
>> 1 2
>> 1 5
>>
>> I'm using 2.10 on Linux, the user reported from 2.9 on Windows.
>>
>> 1. Minor issue: I think the root rounding occurs in factor. I didn't
>> see any discussion of this in the help page, perhaps something should be
>> added.
>>
>> 2. The error popped up in summary.survfit but the root cause is an
>> inconsistent survfit object. The survfit routine uses sort and unique
>> to create the unique survival times and most of the output, but table to
>> count them for another component.
>> Lumping the two versions of "2.0000...." together is the preferable
>> output. I think the best solution will be to preprocess the time
>> variable so that the three operators are consistent.
>>
>> as.numeric(as.character(as.factor(time))) ?
>>
>> Rather ugly. But most importantly what is a guarranteed construct that
>> would ensure consistency? Should we use a rounding level that is more
>> or less equivalent to all.equal()?
>>
>> The solution will have to be incorporated into survfit, coxph, ...
>> perhaps a dozen places in the survival suite so I'd like to get it right
>> the first time.
>>
>> Terry T
>>
>> ______________________________________________
>> R-devel_at_r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>



R-devel_at_r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel Received on Thu 22 Jul 2010 - 20:59:06 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Fri 23 Jul 2010 - 13:40:18 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-devel. Please read the posting guide before posting to the list.

list of date sections of archive