match(x,table) and x%in%table work when x and table are lists of language
objects or expressions. E.g.,
expression(quote(1+2), quote(log2(16))) %in% expression(3, quote(1+2),
c(4L,5L,6L,7L))
#[1] TRUE FALSE
list(quote(1+2), quote(log2(16))) %in% list(3, quote(1+2), c(4L,5L,6L,7L))
#[1] TRUE FALSE
match(list(quote(1+2), quote(log2(16))), list(3, quote(1+2),
c(4L,5L,6L,7L)))
#[1] 2 NA
With your example data:
spList[1] %in% spList
#[1] TRUE
list(quote(foo)) %in% spList
#[1] TRUE
list(quote(nosuchsymbol)) %in% spList
#[1] FALSE
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Tue, Aug 25, 2015 at 9:12 AM, Ben Bolker <bbol...@gmail.com> wrote:
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> I haven't yet dug into the internals of match() yet to see what's
> going on, but I'm wondering whether there's a design reason why I
> can't use %in% (which is a wrapper for match()) on language objects.
>
> I'd like to test whether a language object is in a list of language
> objects, but I get the error "'match' requires vector arguments":
>
> specials <- c("foo","bar")
> spList <- lapply(specials,as.name) ## convert to language objects
> "a" %in% spList ## works (FALSE)
> spList[[1]] %in% spList ## 'match' requires vector arguments
> quote(foo) %in% spList ## ditto
> quote(foo) == spList[[1]] ## TRUE
>
> obviously I can go the other way, converting my target into text:
>
> deparse(spList[[1]]) %in% specials ## TRUE
>
> I could also write my own function to loop through the list and stop
> when I find it. But I'd prefer to use built-in functionality if possible.
>
> Does anyone have any clues/see what I'm missing?
>
> cheers
> Ben Bolker
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