[R] How do I access a specific element of a multi-dimensional list

[William Dunlap]

Using lapply() where Jim used sapply() would keep the types
right and be a fair bit faster than a solution based on repeatedly
appending to a list (like your getFirst).

Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Fri, Feb 20, 2015 at 1:52 PM, JS Huang <js.huang at protective.com> wrote:

> Hi,
>
>   Jim's answer is neat.  There is an issue on the result.  All are
> characters even though some are numeric or logic.  The following
> implementation retains the variable type.
>
> > x
> [[1]]
> [1] 2 3 5
>
> [[2]]
> [1] "aa" "bb" "cc"
>
> [[3]]
> [1]  TRUE FALSE  TRUE
>
> > getFirst
> function(aList)
> {
>   result <- list()
>   for (i in 1:length(aList))
>   {
>     result <- c(result, aList[[i]][1])
>   }
>   return(result)
> }
> > getFirst(x)
> [[1]]
> [1] 2
>
> [[2]]
> [1] "aa"
>
> [[3]]
> [1] TRUE
>
> >
>
>
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/How-do-I-access-a-specific-element-of-a-multi-dimensional-list-tp4703596p4703622.html
> Sent from the R help mailing list archive at Nabble.com.
>
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