[Rd] possible bug in 'scan'

[Prof Brian Ripley]

On Tue, 26 Jun 2007, Benjamin Tyner wrote:

> R-devel,
>
> When I run the following code on the attached file,
>
> tmp <- scan("C:/temp.csv",
>           what=list("character","numeric"),
>           sep=",")
>
> Then tmp[[2]] is a character vector. My impression from the help file
> is that it should be a numeric as specified by 'what'

No, as "numeric" is a character vector.

     what: the type of 'what' gives the type of data to be read. The
           supported types are 'logical', 'integer', 'numeric',
           'complex', 'character', 'raw' and 'list'. If 'what' is a
           list, it is assumed that the lines of the data file are
           records each containing 'length(what)' items ("fields") and
           the list components should have elements which are one of the
           first six types listed or 'NULL', see section 'Details'
           below.

so you need what = list("", 0), say.

There are even examples in 'An Introduction to R'.

>
>> sessionInfo()
> R version 2.5.0 (2007-04-23)
> i386-pc-mingw32
>
> locale:
> LC_COLLATE=English_United States.1252;LC_CTYPE=English_United
> States.1252;LC_MONETARY=English_United
> States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252
>
> attached base packages:
> [1] "stats"     "graphics"  "grDevices" "utils"     "datasets"
> "methods"   "base"
>
> other attached packages:
> lattice    gdata
> "0.15-5"  "2.3.1"
>
> My apologies if this is due to my misunderstanding.
> Ben
>

-- 
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