Re: [R] Data.frames : difference between x$a and x[, "a"] ? - How set new values on x$a with a as variable ?

[omerle]

> Message du 10/09/10 14:53
> De : "Ista Zahn"
> A : "omerle"
> Copie à : r-help@r-project.org
> Objet : Re: [R] Data.frames : difference between x$a and x[, "a"] ? - How set 
> new values on x$a with a as variable ?
>
>
> Hi,
>
> On Fri, Sep 10, 2010 at 4:05 AM, omerle wrote:
> > Hi,
> >
> > I got two questions :
> >
> > 1st Question
> >             a="S"
> >             b=data.frame(S=3)
> >             do.call(`<-`,list(do.call(`$`,list(b,"S")),5))
>
> I think there is some confusion here. Why are you setting a equal to
> "S" but then never using it?
>
> > => How can I put new values on S column having the column name as a 
> > variable ?
>
> I'm having trouble parsing this. What exactly do you want to do?
1 - Put a list as an element of a data.frame. That's quite convenient for my 
pricing function.
 
> >
> > 2 nd Question
> >        a="S"
> >        b=data.frame(S=3)
> >        b[,"S"]=list(1:10) #Doesnt works
> >        b$S=list(1:10) #Works
> > => Isnt the same thing ? What is the difference between these two things ?
>
> I believe b[["S"]] is the same as b$S, b[,"S"] is different. But I
> have to question your assertion that b$S=list(1:10) "Works". This is a
> very odd construction (putting a list as an element of a data.frame)
> and is almost certainly not what you want.
2 - That's what I want. I figured out just five minutes ago that b[["S"]] works 
because it's the same thing as b$S.
But I still dont know what is b[,"S"] compared to b[["S"]]
> >
> >
> > Thanks,
> >
> > Une messagerie gratuite, garantie à vie et des services en plus, ça vous 
> > tente ?
> > Je crée ma boîte mail www.laposte.net
> >
> >        [[alternative HTML version deleted]]
> >
> >
> > ______________________________________________
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> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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> >
> >
>
>
>
> --
> Ista Zahn
> Graduate student
> University of Rochester
> Department of Clinical and Social Psychology
> http://yourpsyche.org
>
> 

Une messagerie gratuite, garantie à vie et des services en plus, ça vous 
tente ?
Je crée ma boîte mail www.laposte.net

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