[R] cut POSIX results in NA - bug?
Prof Brian Ripley
ripley at stats.ox.ac.uk
Wed Nov 3 12:20:57 CET 2004
On Wed, 3 Nov 2004, Petr Pikal wrote:
> Dear all
> I try to make hourly average by cut() function, which almost works
> as *I* expected. What puzled me is that if there is only one item at
> the end of your data it results in NA.
> Example will explain what I mean
> datum<-seq(ISOdate(2004,8,31), ISOdate(2004,9,1), "min")
> cut(datum[1370:1381],"hour", labels=F)
>  1 1 1 1 1 1 1 1 1 1 1 NA
> cut(datum[1370:1382],"hour", labels=F)
>  1 1 1 1 1 1 1 1 1 1 1 2 2
> I do not understand why the last item in first call is NA. I found it
> only when there was a switch from DST to standard time as it
> coused a trouble in one of my functions and I found there is NA
> value where I did not expected it.
cut(datum[1370:1381],"hour", labels=F, include.lowest=T)
is what you need. See ?cut, in the See Also, which says
include.lowest: logical, indicating if an 'x[i]' equal to the lowest
(or highest, for 'right = FALSE') 'breaks' value should be
> I can make some workaround but can you please explain me why
> first call results in NA value at the end of a vector and if it is
> *intended* behaviour.
It is the documented behaviour, for better or for worse.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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