[Rd] factors in data.frames (PR#835)
ripley@stats.ox.ac.uk
ripley@stats.ox.ac.uk
Thu, 1 Feb 2001 11:15:26 +0100 (MET)
> From: james.lindsey@luc.ac.be
> Date: Thu, 1 Feb 2001 10:56:07 +0100 (MET)
>
> The following seems to be a contradiction:
What is, pray?
> class(df[, 1])
[1] "factor"
> class(df[, 1, drop = FALSE])
[1] "data.frame"
df[ , 1, drop=FALSE] is a data frame, so not a factor.
df[ , 1] is a factor.
> > df <- data.frame(x=gl(2,1,10))
> > df[,1]
> [1] 1 2 1 2 1 2 1 2 1 2
> Levels: 1 2
> > df[,1,drop=F]
> x
> 1 1
> 2 2
> 3 1
> 4 2
> 5 1
> 6 2
> 7 1
> 8 2
> 9 1
> 10 2
> > is.factor(df[,1,drop=F])
> [1] FALSE
> > is.factor(df[,1])
> [1] TRUE
>
> with R1.2.1 both MS Windows and Intel RH5.2 versions.
> Jim
--
Brian D. Ripley, ripley@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
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