From sfalcon at fhcrc.org  Tue Mar  7 17:56:32 2006
From: sfalcon at fhcrc.org (Seth Falcon)
Date: Tue, 07 Mar 2006 08:56:32 -0800
Subject: [Rd] possible bug: NULL equality in lists.
In-Reply-To: <440DABCA.6030108@statistik.uni-dortmund.de> (Uwe Ligges's
	message of "Tue, 07 Mar 2006 16:50:34 +0100")
References: <440D9B1E.6020001@vanderbilt.edu>
	<440DA2FE.8050709@statistik.uni-dortmund.de>
	<m2wtf6w9jr.fsf@ziti.local>
	<440DABCA.6030108@statistik.uni-dortmund.de>
Message-ID: <m2slpuw5vj.fsf@ziti.local>

Uwe Ligges <ligges at statistik.uni-dortmund.de> writes:
> These are all dangerous, hence use the "safe" ways:
>
> sapply(a, is.null)
> sapply(a, identical, "NULL")
> sapply(a, is.na)
> sapply(a, identical, "NA")

Point taken, but is the behavior of as.character correct?

as.character(list(NULL))

as.character(NULL)

+ seth



[Rd] possible bug: NULL equality in lists.
Seth Falcon