[R] sample

[Liaw, Andy]

?sample says:

x   Either a (numeric, complex, character or logical) vector of more
    than one element from which to choose, or a positive integer 

so I guess it wasn't meant to be used on a data frame.  However, a data
frame is a list (where the variables are the components), and a list is a
vector, so the behavior is consistent:

> x <- list("a", 2, "c", 4, "e", "f")
> sample(x)
[[1]]
[1] "c"

[[2]]
[1] "a"

[[3]]
[1] 4

[[4]]
[1] 2

[[5]]
[1] "f"

[[6]]
[1] "e"

Andy

> From: Jean Eid
> 
> It seems that sample picks columns when the object is turned into a
> data.frame. I do not knoe why it is doing that....
> 
> Is this something that was meant and not documented or something?
> 
> 
> Jean
> 
> 
> On Fri, 11 Feb 2005, Adaikalavan Ramasamy wrote:
> 
> > See below.
> >
> > On Thu, 2005-02-10 at 14:53 -0800, T. Murlidharan Nair wrote:
> > > Just to explain my previous mail, here is the output I get.
> > >
> > >
> > >  > dim(tissue.exp)
> > > [1] 1532   20
> >
> > What is this object ? Try class(tissue.exp)
> >
> > >  > pick<-sample(tissue.exp,5,replace=TRUE)
> > >  > dim(pick)
> > > [1] 1532    5
> >
> > >From help(sample) :
> >
> >     sample(x, size, replace = FALSE, prob = NULL)
> >
> >     x: Either a (numeric, complex, character or logical) vector of
> >        more than one element from which to choose, or a positive
> >        integer.
> >
> > x has to be a vector or positive integer integer. I am not 
> sure how you
> > got "sample" to work on tissue.exp in the first place. Maybe you got
> > your own version of "sample".
> >
> >
> > >  > tissue.exp.t<-t(tissue.exp)
> > >  > dim(tissue.exp.t)
> > > [1]   20 1532
> > >  > pick<-sample(tissue.exp.t,5,replace=TRUE)
> > >  > dim(pick)
> > > NULL
> > >
> > > --------
> > > Thanks ../Murli
> > >
> > > ______________________________________________
> > > R-help at stat.math.ethz.ch mailing list
> > > https://stat.ethz.ch/mailman/listinfo/r-help
> > > PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
> > >
> >
> > 
> ______________________________________________
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> 
> 
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