[R] R 1.2.1 - read.table - factors problem or is it a data.frame problem

Martin Maechler maechler at stat.math.ethz.ch
Fri Feb 2 08:44:51 CET 2001

>>>>> "PD" == Peter Dalgaard BSA <p.dalgaard at biostat.ku.dk> writes:

    PD> "Heberto Ghezzo" <Heberto at meakins.lan.mcgill.ca> writes:
    >> I have some problems with read.table and floats turning up as 
    >> factors. In my case it was not a blank in the file but an unary minus!!
    >> so 3.24,-57.23,... the 3.24 is numeric but -57.23 is a factor.
    >> Yes I turned it into a numeric with as.numeric(as.character(.. but I 
    >> think it will be better to modify somehow the read.table/read.csv 
    >> code.
    >> Thanks anyway.

    PD> That certainly sounds like a bug, but I can't reproduce it:

    PD> $ cat > xx  
    PD> -1,2,3
    PD> 1,-2,3
    PD> $ R
    PD> ...
    >> summary(read.csv('xx',head=F))
    PD> V1             V2           V3   
    PD> Min.   :-1.0   Min.   :-2   Min.   :3  
    PD> 1st Qu.:-0.5   1st Qu.:-1   1st Qu.:3  
    PD> Median : 0.0   Median : 0   Median :3  
    PD> Mean   : 0.0   Mean   : 0   Mean   :3  
    PD> 3rd Qu.: 0.5   3rd Qu.: 1   3rd Qu.:3  
    PD> Max.   : 1.0   Max.   : 2   Max.   :3  

    PD> Could you give us some further details on the setup that is causing
    PD> that effect?

Heberto uses a Windoze mailer, hence probably ..

It could be that the problem comes from the fact that some win users
use non-ASCII minus characters (i.e. not "minus", but these find them on
their keyboards when typing in the data ..):

In iso_8859-1 aka "latin-1" (of which most European MSWin localizations are
   said to be a superset) there are three kinds of "-" :

       Oct   Dec   Hex   Char   Description
       055   45    2D     -     Minux  [The standard ASCII one]

       255   173   AD     ­     SOFT HYPHEN

       257   175   AF     ¯     MACRON

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