[R] Newbie question: histogram

John Fox jfox at mcmaster.ca
Wed Feb 4 20:25:38 CET 2004

Dear Martin,

At 06:07 PM 2/4/2004 +0100, Martin Maechler wrote:
> >>>>> "JohnF" == John Fox <jfox at mcmaster.ca>
> >>>>>     on Wed, 04 Feb 2004 09:20:43 -0500 writes:
>     JohnF> Dear Philippe, I suppose that you want a histogram
>     JohnF> for snow.cover and not for year. There are several
>     JohnF> ways to proceed; two are
>     JohnF> hist(mydata$snow.cover)
>     JohnF> and
>     JF> attach(mydata)
>     JF> hist(snow.cover)
>Actually, attaching data frames is a bit discouraged these days.
>The modern R way for this (and more complicated situations) is
>   with(mydata,  hist(snow.cover) )

Although I'm aware of (some of) the problems and possibly confusing 
situations that can arise from attaching a data frame, I believe that, 
especially for novice users, there's an advantage in doing so. In 
particular, although using with() is perhaps less ambiguous, it is 
necessary to repeat it for each command.


>     JohnF> More generally, it's a good idea to read the
>     JohnF> introductory manual that comes with R (or a book that
>     JohnF> introduces R). See, in particular, the section on
>     JohnF> lists and data frames in the Introduction to R.

John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox at mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox

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