Message-ID: <14525.11398.674344.77690@lynne.ethz.ch>
Date: 2000-03-01T14:43:18Z
From: Martin Maechler
Subject: "is.qr" definition (PR#465)
In-Reply-To: <200003011113.MAA25485@pubhealth.ku.dk>
>>>>> "JonR" == J C Rougier <J.C.Rougier@durham.ac.uk> writes:
JonR> Might it be possible to tighten the definition of "is.qr". I
JonR> noticed that after I mistakenly typed
JonR> example(lm) # make lm object named lm.D9
JonR> qr.Q(lm.D9)
JonR> which exhausted the heap memory and produced two warning
JonR> messages. As an object of class "lm" has a "qr" component,
JonR> "is.qr" failed to detect that "lm.D9" was not a "qr" object.
indeed.
yes, it should be tightened.
JonR> The obvious thing might be to tighten the definition of "is.qr",
JonR> perhaps
JonR> "is.qr" <- function(x) all(c("qr", "rank", "qraux", "pivot") %in%
JonR> names(x))
Just checked:
S-plus 5.1 checks for qr and qraux only (but not just for the presence of
the names, also !is.null(.) as we now do for $qr.
It makes sense to have this a FAST function since it's called quite a few
times in some calculations... maybe change current
is.qr <- function(x) is.null(x$qr)
to
is.qr <- function(x) is.null(x$qr) && !is.null(x$rank) && !is.null(x$qraux)
The current behavior is "according to documentation" so that would have to
be updated as well.
JonR> And may I add my congratulations to the core group.
thank you
Martin Maechler <maechler@stat.math.ethz.ch> http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum LEO D10 Leonhardstr. 27
ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND
phone: x-41-1-632-3408 fax: ...-1228 <><
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