text() does not accept data of type POSIXlt (PR#2487) - R-devel

Wed, Jan 22, 2003 6:53 AM #

[R 1.6.1]

PROBLEM
    If text() is called with an argument of type POSIXlt,
    I get the following error message:

        "Error in as.double.default(x) :
        (list) object cannot be coerced to vector type 14"

REMARK
    plot() accepts this data.

EXAMPLE
    data( Lifeboats, package='vcd' )
    attach(Lifeboats)
    plot( launch, total )
    text( launch, total, labels=seq( along=as.vector( launch ) ) )
    detach(Lifeboats)


Wolfram Fischer

Brian Ripley

Wed, Jan 22, 2003 7:14 AM #

Where is the R bug here?

The dates are *NOT* `of type POSIXlt': they are of type list but
class c("POSIXt", "POSIXlt")

plot() is a generic function with a POSIXlt method.
text() has no POSIXt nor POSIXlt method.

Nothing says that an arbitrary function you choose will accept arbitrary 
input, nor that plot and points, lines, text etc will have compatible 
methods: there are dozens of exceptions.

On Wed, 22 Jan 2003 wolfram@fischer-zim.ch wrote:

Brian D. Ripley,                  ripley@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

wolfram at fischer-zim.ch

Wed, Jan 22, 2003 10:32 AM #

Thanks for your hint about POSIXt and POSIXlt.

Excuse me that I bothered you with my message.

I thought that text() is a function which is used often in 
combination with plot(). I have the opinion that it would be
helpful if such functions are harmonised as good as possible. -
Therefore I took the time to inform about my observation.

Wolfram Fischer

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