blues in c - R-help | R Mailing Lists

Tue, Sep 25, 2001 6:24 AM #

G'Day,

I'm a little  confused why the c function has the followng effect on
classes - is this a feature ?  My workround [ class(cc) <- c("POSIXt",
"POSIXct") ] seems to do the job.

Many thanks

Bernie McConnell


"R version 1.3.1, 2001-08-31" on NT

Time difference of -1 days

[1] "1969-12-31 GMT Standard Time"
Warning message: 
Incompatible methods ("-.POSIXt", "-.POSIXct") for "-"

[1] "POSIXt"  "POSIXct"

[1] "POSIXct"

Time difference of -1 days

Bernie McConnell
NERC SEA MAMMAL RESEARCH UNIT
Gatty Marine Lab, St Andrews University
St Andrews, Fife,  KY16 8LB, Scotland.

b.mcconnell at smru.st-andrews.ac.uk
http://www.smru.st-and.ac.uk
tel:  	+44 (1334) 463280   
fax:  	+44 (1334) 462632   


                
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Brian Ripley

Tue, Sep 25, 2001 6:50 AM #

On Tue, 25 Sep 2001, Bernie McConnell wrote:

It's a legacy

c.POSIXct <- function(..., recursive=FALSE)
    structure(c(unlist(lapply(list(...), unclass))),
class=c("POSIXt","POSIXct"))

does the job.

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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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Peter Dalgaard

Tue, Sep 25, 2001 6:55 AM #

Prof Brian Ripley <ripley at stats.ox.ac.uk> writes:

Speaking of the devil... Is there any reason as.POSIXct shouldn't work
on numeric data?

Error in as.POSIXct.default(0) : Don't know how to convert `0' to class "POSIXct"

[1] "1970-01-01 01:00:00 CET"

(Discovered by trying

c.POSIXct <- function(..., recursive=FALSE)
    as.POSIXct(c(unlist(lapply(list(...), unclass))))

)

O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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Brian Ripley

Tue, Sep 25, 2001 7:02 AM #

On 25 Sep 2001, Peter Dalgaard BSA wrote:

Yes, there is no way to know what it means.  Numeric data is not a date!

Yes, that works, but you need to know the meaning of the numeric vector.

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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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