[R] Splitting a set of vectors in a list (Solved )

[John Kane]

--- "Liaw, Andy" <andy_liaw at merck.com> wrote:

> From: Bert Gunter
>  
> > ?"["  ?InternalMethods
> > 
> > x[i,j] is just shorthand for  "["(x,i,j) .
> (AFAIK)**All** operators
> > (+,-,...,subscripting,...) in R are functions,
> stemming from 
> > its LISP-like
> > heritage, and can actually called by the usual
> functional 
> > syntax, f(...),
> > instead of the operator syntax.
> 
> That is true even for assignment:
> 
> R> "<-"(junk, 1:3)
> R> junk
> [1] 1 2 
Okay I think I've got this one but

> and "{":
>
> R> "{"(1, 2, 3)
this defeats me. I see what it is doing but I have not
the slightest idea why . 

I had a look at ?"{" and if I am understanding the
example {2+3; 4+5}  what is happening is that anything
within the {} is being executed as separate statments
but I have not the slightest idea of what is happening
when "{"(1, 2, 3) returns 3.  

The other thing is, is it worth trying to figure out
what appears to be rather esotheric coding if I can do
the same with more intuitively understood albeit
clumsier code? 


> 
> I believe this is in the (draft) R Language
> Definition, part of the
> official manuals that shipped with R.
> 
> Andy
>  
> > Not sure where this is explicitly discussed within
> R's 
> > documentation, but
> > you can find info on it in V&R's "S Programming",
> esp. p.24 and 4.3,
> > "Extracting or replacing coefficients".
> > 
> > No doubt, other S/R  books explain it also.
> > 
> > Cheers,
> > 
> > Bert Gunter
> > Genentech Nonclinical Statistics
> > 47374
> > 
> > 
> > -----Original Message-----
> > From: r-help-bounces at r-project.org 
> > [mailto:r-help-bounces at r-project.org] On
> > Behalf Of John Kane
> > Sent: Thursday, March 13, 2008 11:53 AM
> > To: Henrique Dallazuanna
> > Cc: R R-help
> > Subject: Re: [R] Splitting a set of vectors in a
> list (Solved )
> > 
> > My thanks to Henrique Dallazuanna and Phil
> Spector. 
> > Both solutions worked well. 
> > Phil suggested that an alterative to my function
> would
> > be 
> > vect1 = sapply(mylist,'[[',1)
> > and I see that Henrique used `[` in his solution.
> > 
> > Can you point me to some documentation that
> discusses
> > these usages. I have seen them before but I have
> never
> > actually figured out how to use them.? 
> > 
> > Thanks.
> > 
> > Problem and solutions
> >
>
========================================================
> > mylist <- list(aa=c("cat","peach" ), bb=c("dog",
> > "apple", "iron"), 
> >          cc = c("rabbit", "orange", "zinc",
> "silk"))
> > myfun <- function(dff) dff[1]       
> > vect1  <- unlist(lapply(mylist, myfun))
> > 
> > # Desired output
> > t(cbind( c("cat" ,  "peach" , NA, NA), bbb  <-
> c("dog"
> > ,  "apple" ,"iron", NA),
> > ccb <- c("rabbit" ,"orange" ,"zinc" ,  "silk" ))) 
> > 
> > # Phil Spector's approach
> > mlen = max(sapply(mylist,length))
> > eqlens = lapply(mylist,function(x)if(length(x) <
> mlen)
> >                            
> > c(x,rep('',mlen-length(x))) else x)
> > do.call(rbind,eqlens)
> > 
> > # 	"Henrique Dallazuanna" <wwwhsd at gmail.com>
> > #    I added the t()
> > t(as.data.frame(lapply(mylist, `[`,
> > 1:max(unlist(lapply(mylist,
> >  length))))))
> > 
> > 
> > [[elided trailing spam]]
> > 
> > ______________________________________________
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> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide 
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained,
> reproducible code.
> > 
> > ______________________________________________
> > R-help at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide 
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained,
> reproducible code.
> > 
> > 
> > 
> 
> 
>
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