>>>>> peter dalgaard
>>>>> on Fri, 16 Nov 2018 13:39:27 +0100 writes:
> Well, "Basically, " is an excuse for not being
> accurate. Making the code more complex doesn't really help
> the explanation. It could be better to just add "(except
> for NA handling)" or so.
> -pd
or --- applying Swiss diplomacy finding a way-between ;-) ---
" Basically, the result is (1:length(x))[x], or to cover more
cases, including when x has NA's,
seq_along(x)[!is.na(x) & x] "
to also cover the 0-length case and come pretty close to the "truth".
Martin
>> On 16 Nov 2018, at 11:08 , buzon informatica, ige
>> <ige.informat...@ige.eu> wrote:
>>
>> The which() function help page states that, in the
>> default case, what the function returns is: " Basically,
>> the result is (1:length(x))[x]." That would only be true
>> if there are not any NA values in x. I think it would be
>> more accurate to say: "Basically, the result is
>> (1:length(x))[!is.na(x) & x]."
>>
>> The "strange" (IMHO) behavior of logical indexing in R
>> makes it necessary to exclude NA values. For this
>> reason, I use to wrap logical indices with which(). I
>> would have written the above expression as:
>> (1:length(x))[which(x)] But that would have been a really
>> bad explanation of how the which() function works ;)
>>
>> [[alternative HTML version deleted]]
>>
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> --
> Peter Dalgaard, Professor, Center for Statistics,
> Copenhagen Business School Solbjerg Plads 3, 2000
> Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23
> Email: pd....@cbs.dk Priv: pda...@gmail.com
> ______________________________________________
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and
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