# Re: [R] creating a data frame from a list

From: Stephen Tucker <brown_emu_at_yahoo.com>
Date: Fri 06 Apr 2007 - 07:40:24 GMT

Hi Dimitri,

You can try this one if you'd like:

lst = list(a=c(A=1,B=8) , b=c(A=2,B=3,C=0), c=c(B=2,D=0)) # get unique names
nms <- unique(rapply(lst,function(x) names(x))) # create a vector of NA's and then fill it according # to matching names for each element of list doit <- function(x,nms) {
y <- rep(NA,length(nms)); names(y) <- nms   y[match(names(x),names(y))] <- x
return(y)
}
# apply it to the data
dtf <- as.data.frame(sapply(lst,doit,nms))

• Dimitri Szerman <dimitrijoe@gmail.com> wrote:

> Dear all,
>
> A few months ago, I asked for your help on the following problem:
>
> I have a list with three (named) numeric vectors:
>
> > lst = list(a=c(A=1,B=8) , b=c(A=2,B=3,C=0), c=c(B=2,D=0) )
> > lst
> \$a
> A B
> 1 8
>
> \$b
> A B C
> 2 3 0
>
> \$c
> B D
> 2 0
>
> Now, I'd love to use this list to create the following data frame:
>
> > dtf = data.frame(a=c(A=1,B=8,C=NA,D=NA),
> + b=c(A=2,B=3,C=0,D=NA),
> + c=c(A=NA,B=2,C=NA,D=0) )
>
> > dtf
> a b c
> A 1 2 NA
> B 8 3 2
> C NA 0 NA
> D NA NA 0
>
> That is, I wish to "merge" the three vectors in the list into a data frame
> by their "(row)"names.
>
> And I got the following answer:
>
> library(zoo)
> z <- do.call(merge, lapply(lst, function(x) zoo(x, names(x))))
> rownames(z) <- time(z)
> coredata(z)
>
> However, it does not seem to be working. Here's what I get when I try it:
>
> > lst = list(a=c(A=1,B=8) , b=c(A=2,B=3,C=0), c=c(B=2,D=0) )
> > library(zoo)
> > z <- do.call(merge, lapply(lst, function(x) zoo(x, names(x))))
> Error in if (freq > 1 && identical(all.equal(freq, round(freq)),
> TRUE)) freq <- round(freq) :
> missing value where TRUE/FALSE needed
> NAs introduced by coercion
>
> and z was not created.
>
> Any ideas on what is going on here?
> Thank you,
> Dimitri
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Be a PS3 game guru.

R-help@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 and provide commented, minimal, self-contained, reproducible code. Received on Fri Apr 06 17:50:18 2007

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.1.8, at Fri 06 Apr 2007 - 08:31:01 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.