On 15/09/2014 16:30, Samuel Knapp wrote:
Dear all,
I have discovered a bug in the standard rep() function: At certain
Not so:
> a <- (1-0.9)*100
> trunc(a)
[1] 9
As the help says
Non-integer values of ‘times’ will be truncated towards zero. If
‘times’ is a computed quantity it is prudent to add a small fuzz.
And as the posting guide said
Do your homework before posting:
...
Read the online help for relevant functions (type ?functionname,
e.g., ?prod, at the R prompt)
values, rep() does not replicate the element by the proper number of times:
> a <- (1-0.9)*100
> a
[1] 10
> length(rep(1,times=a))
[1] 9
> length(rep(1,each=a))
[1] 9
As shown, this happens as well for the times= as for the each=
parameter. It does not depend on the kind of element that is to be
repeated:
> length(rep("abc",each=a))
[1] 9
I tried to narrow down the bug, but haven't really managed to find a
pattern behind the bug. Here is a list with values for a (see above)
that returns a false object ( after the value for a, i've collected the
expected length and the length that is produced by r):
# mistake at
(1-0.9)*100 10 9
(1-0.8)*100 20 19
(1-0.8)*1000 200 199
(1-0.9)*1000 100 99
(1-0.9)*10 1 0
(1-0.8)*10 2 1
(1-0.9)*1000000000 100000000 99999999
(2-1-0.9)*100 10 9
(10/10-0.9)*100 10 9
# the following sets for a work fine
(1+0.1)*100
(1-0.1)*100
(1-0.7)*100
(1-0.99)*1000
(1-0.7)*10
(1-0.90)*10
(1-0.95)*100
(1-0.95)*1000
(2-0.9)*1000
(2-1.9)*100
(1.1-1)*100
(10-9)*100
Did I make any mistake? Or where else should I address this problem?
Thanks and best regards,
Samuel
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--
Brian D. Ripley, rip...@stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford
1 South Parks Road, Oxford OX1 3TG, UK
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
