From maechler@stat.math.ethz.ch  Fri Oct 29 15:45:34 1999
From: maechler@stat.math.ethz.ch (maechler@stat.math.ethz.ch)
Date: Fri, 29 Oct 1999 16:45:34 +0200 (MET DST)
Subject: expand.grid() (PR#301)
Message-ID: <199910291445.QAA13256@pubhealth.ku.dk>

>>>>> "JonR" == J C Rougier <J.C.Rougier@durham.ac.uk> writes:

    JonR> This is a very minor point and I hesitate to call it a bug, but
    JonR> might I suggest modifying the nargs=1 return statement in
    JonR> expand.grid() from

    JonR>     if (nargs == 1) return(args[[1]])

    JonR> to

    JonR>     if (nargs == 1) return(data.frame(args))

    JonR> so that the result of expand.grid is always a data frame (as
    JonR> indicated in the help file).  This also preserves the variable
    JonR> name if it exists.

Well, that is not quite true,

      expand.grid(NULL)  

gives NULL  without your change 
but gives an error with your change...
since
	data.frame(NULL)  
fails.

The following (only this one of all 4 possibilities  as/no-as  x NULL/list() )
would work

> as.data.frame(list())
NULL data frame with 0 rows

---
Better patch ? (and what does S do ?)

Martin

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expand.grid() (PR#301)
maechler@stat.math.ethz.ch