From Mark.Bravington at csiro.au  Tue Apr 29 10:25:41 2014
From: Mark.Bravington at csiro.au (Mark.Bravington at csiro.au)
Date: Tue, 29 Apr 2014 08:25:41 +0000
Subject: [Rd] type.convert and doubles
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[...snip...]
Martin Maecher wrote:

> > I have now committed svn rev 65507  --- to R-devel only for now ---
> > the above:   exact = NA  is the default
> > and it means  "warning + FALSE".
> >
> > Interestingly, I currently get 5 identical warnings for one
> > simple call, so there seems clearly room for optimization, and
> > that is one main reason for this reason to not yet be migrated
> > to 'R 3.1.0 patched'.

Peter Dalgaard wrote:
> I actually think that the default should be the old behaviour. No warning, just potentially lose digits. If this gets a user in trouble, _then_ turn on the check for lost digits.

+1

IMO "read.table" and friends are convenience functions with somewhat of a "do what I mean" flavour, and as such their default should be to work conveniently for most cases. We typically ignore loss of precision in all sorts of numeric operations without warning. Those who do really care about that 21st digit in 'read.table' could always use 'colClasses'. With a 'digitloss' argument (but shouldn't it be column-specific? if not, is it really needed?) they can get what they need more easily, but the evidence seems to be that this is a rare case.

Mark Bravington
CSIRO
Hobart
Australia


[Rd] type.convert and doubles
Mark.Bravington at csiro.au