Splitting vector into individual elements

From: Liaw, Andy

From: Paul Roebuck

On Wed, 15 Sep 2004, Peter Dalgaard wrote:

Paul Roebuck <roebuck at odin.mdacc.tmc.edu> writes:

Is there a means to split a vector into its individual
elements without going the brute-force route for arguments
to a predefined function call?

    offred.rgb <- c(1, 0, 0) * 0.60;

    ## Brute force style
    offred.col <- rgb(offred.rgb[1],
                      offred.rgb[2],
                      offred.rgb[3],
                      names = "offred")
    ## Desired style
    offred.col <- rgb(silver.bullet(offred.rgb),
                      names = "offred")

The closest is probably this:

offred.col <- do.call("rgb", c(as.list(offred.rgb),
                               list(names="offred")))

Everyone offered 'do.call' as the solution. While that
works, is it to say that there is no means of expanding
the expression as an argument to the original function?

What would be the point?  That's what do.call() does for you 
internally.

toCall <- c(as.name("rgb"), as.list(offred.rgb), names="offred")
toCall

toCall <- as.call(toCall)
toCall

eval(toCall)

Andy
 

(ever read/seen The Handmaid's Tale, btw?)

Not yet. Though renaming my sample variable 'off.red.col'
would avoid future confusion with oppressed handmaids.

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