Hi R-devel,
Today I was needing a way to "merge" two different lists (see the
example
for my definition of merge). I didn't find anything relevant using
different search methods.
So, here is my proposal to add a list method for "merge".
Best wishes,
Eric
PS: AFAIK, there still is no place for code snipplets. I am not sure this
mail doesn't suite R-devel. If not, what place could there be for
discussions/proposal on such code snipplets?
-- CODE
merge.list=function(x,y,only.new.y=FALSE,append=FALSE,...)
{
out=x
ystructure = names(c(y,recursive=TRUE))
xstructure = names(c(x,recursive=TRUE))
yunique = ystructure[! ystructure %in% xstructure]
ystructure = sapply(ystructure,FUN=function(element)
strsplit(element,"\\."))
xstructure = sapply(xstructure,FUN=function(element)
strsplit(element,"\\."))
yunique = sapply(yunique,FUN=function(element)
strsplit(element,"\\."))
if (only.new.y) lapply(yunique, FUN=function(index)
out[[index]]<<-y[[index]])
else
{
if (!append){
lapply(ystructure, FUN=function(index)
out[[index]]<<-y[[index]])
}
else lapply(ystructure, FUN=function(index)
out[[index]]<<-c(out[[index]],y[[index]]))
}
return(out)
}
-- SAMPLE
> (l1=list(a=list(a1=1,a2=2),b=list(b1=1)))
$a
$a$a1
[1] 1
$a$a2
[1] 2
$b
$b$b1
[1] 1
> (l2=list(a=list(a1=-1,a3=3),c=pi))
$a
$a$a1
[1] -1
$a$a3
[1] 3
$c
[1] 3.141593
> merge(l1,l2)
$a
$a$a1
[1] -1
$a$a2
[1] 2
$a$a3
[1] 3
$b
$b$b1
[1] 1
$c
[1] 3.141593
> merge(l1,l2,append=TRUE)
$a
$a$a1
[1] 1 -1
$a$a2
[1] 2
$a$a3
[1] 3
$b
$b$b1
[1] 1
$c
[1] 3.141593
> merge(l1,l2,only.new.y=TRUE)
$a
$a$a1
[1] 1
$a$a2
[1] 2
$a$a3
[1] 3
$b
$b$b1
[1] 1
$c
[1] 3.141593
>
--
Eric Lecoutre
UCL / Institut de Statistique
Voie du Roman Pays, 20
1348 Louvain-la-Neuve
Belgium
tel: (+32)(0)10473050
lecoutre@stat.ucl.ac.be
http://www.stat.ucl.ac.be/ISpersonnel/lecoutre
If the statistics are boring, then you've got the wrong numbers. -Edward
Tufte
