Peter,
You're right ... and I do think I've finally understood the help file on this.
I somehow missed the connection between my variable's values, which include
NAs, and the fact that those returned values are in turn indices for '['.
OK ... I'm all straight on this now. (I lost count of how many times I read
the help file ... it'd be great if the help page could be updated with a
specific example on this sublety .... that's just a thought).
Thanks again to all for your patience with me on this,
Mauricio
New Jersey, USA
________________________________
From: Peter Ehlers <ehl...@ucalgary.ca>
Cc: William Dunlap <wdun...@tibco.com>; David Winsemius
<dwinsem...@comcast.net>; peter dalgaard <pda...@gmail.com>;
"r-help@r-project.org" <r-help@r-project.org>
Sent: Tuesday, August 28, 2012 2:08 PM
Subject: Re: [R] Inexplicably different results using subset vs bracket
notation on logical variable
On 2012-08-28 07:44, Mauricio Cornejo wrote:
> William, David, and Peter,
>
>
> Thank you all so much for your help on this. Though I had read the help
> files on 'subset' and '[', I had not been able to discern from that text what
> the problem was. I could not have solved it without your help.
>
>
> The help file on 'subset' mentions "For ordinary vectors, the result is
> simply x[subset & !is.na(subset)]." However, since I was dealing with a data
> frame at the time, I failed to appreciate the relevance (but I get it now).
>
>
> I've gone back to read the help on '[' and I still don't see where this
> functionality is described. The page has section titled "NAs in indexing",
> whose content I interpret as being limited to NAs in the indices (and not in
> the returned values). I can't find any text in the documentation describing
> the subtle behavior you kindly pointed out.
Hmmm, it seems to me that the page is clear:
"... NA index picks an unknown element and so *returns* NA
in the corresponding element of ..."
(my emphasis)
Isn't that exactly what occurs?
Peter Ehlers
>
> Thanks again,
> Mauricio
> [[alternative HTML version deleted]]
>
[[alternative HTML version deleted]]
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