[R] bug in rle?

[Bert Gunter]

Thanks Bill:

Personally, I don't need it. Once Brian made me aware of the
underlying issue, I can handle it.

Cheers,
Bert

Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374

"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
H. Gilbert Welch




On Wed, Jan 8, 2014 at 9:30 AM, William Dunlap <wdunlap at tibco.com> wrote:
> If you need an rle for factor data (or lists, or anything for
> which match(), unique(), and x[i] act in a coherent way), try the
> following.  It is based on the S+, all-S code, version of rle.
>
> (It does not work on data.frames because unique is row oriented
> and match is column oriented for data.frames.  If that were
> changed, it still would need a x[ends,] instead of x[ends] in the
> closing statement.)
>
> myRle <- function (x)
> {
>     if (length(x) == 0) {
>         list(lengths = integer(0L), values = x)
>     }
>     else {
>         x.int <- match(x, unique(x))
>         ends <- c(diff(x.int) != 0L, TRUE)
>         list(lengths = diff(c(0L, seq(along = x)[ends])), values = x[ends])
>     }
> }
>
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com
>
>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
>> Of Bert Gunter
>> Sent: Wednesday, January 08, 2014 8:56 AM
>> To: Prof Brian Ripley
>> Cc: r-help at r-project.org
>> Subject: Re: [R] bug in rle?
>>
>> Thank you Brian for your clear and informative answer. I was
>> (obviously!) unaware of this and appreciate the response.
>>
>> Best,
>> Bert
>>
>> Bert Gunter
>> Genentech Nonclinical Biostatistics
>> (650) 467-7374
>>
>> "Data is not information. Information is not knowledge. And knowledge
>> is certainly not wisdom."
>> H. Gilbert Welch
>>
>>
>>
>>
>> On Wed, Jan 8, 2014 at 8:53 AM, Prof Brian Ripley <ripley at stats.ox.ac.uk> wrote:
>> > On 08/01/2014 16:23, Bert Gunter wrote:
>> >>
>> >> Is the following a bug?
>> >> ##(R version 3.0.2 (2013-09-25)
>> >> ## Platform: i386-w64-mingw32/i386 (32-bit))
>> >>
>> >>
>> >> d <- data.frame(a=rep(letters[1:3],4:6))
>> >>   rle(d$a)
>> >> ##Error in rle(d$a) : 'x' must be an atomic vector
>> >>
>> >> is.atomic(d$a)
>> >> ##[1] TRUE
>> >
>> >
>> > But
>> >
>> >> is.vector(d$a)
>> > [1] FALSE
>> >
>> > The discrepancies in what a 'vector' is in R are very long standing, but a
>> > factor is not a vector.
>> >
>> >
>> >> rle(c(d$a))
>> >
>> >
>> > That loses the class and other attributes, giving a vector.
>> >
>> >> ## Run Length Encoding
>> >> ##  lengths: int [1:3] 4 5 6
>> >>   ##  values : int [1:3] 1 2 3
>> >>
>> >> Cheers,
>> >> Bert
>> >>
>> >> Bert Gunter
>> >> Genentech Nonclinical Biostatistics
>> >> (650) 467-7374
>> >
>> >
>> >
>> > --
>> > Brian D. Ripley,                  ripley at stats.ox.ac.uk
>> > Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
>> > University of Oxford,             Tel:  +44 1865 272861 (self)
>> > 1 South Parks Road,                     +44 1865 272866 (PA)
>> > Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>>
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