[R] rep() fails at times=0.29*100
arun
smartpink111 at yahoo.com
Tue Apr 9 18:58:56 CEST 2013
Possibly R FAQ 7.31
length(rep(TRUE,signif(0.29*100,2)))
#[1] 29
A.K.
----- Original Message -----
From: Jorge Fernando Saraiva de Menezes <jorgefernandosaraiva at gmail.com>
To: r-help at r-project.org
Cc:
Sent: Tuesday, April 9, 2013 12:11 PM
Subject: [R] rep() fails at times=0.29*100
Dear list,
I have found an unusual behavior and would like to check if it is a
possible bug, and if updating R would fix it. I am not sure if should post
it in this mail list but I don't where is R bug tracker. The only mention I
found that might relate to this is "If times is a computed quantity it is
prudent to add a small fuzz." in rep() help, but not sure if it is related
to this particular problem
Here it goes:
> rep(TRUE,29)
[1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[28] TRUE TRUE
> rep(TRUE,0.29*100)
[1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[28] TRUE
> length(rep(TRUE,29))
[1] 29
> length(rep(TRUE,0.29*100))
[1] 28
Just to make sure:
> 0.29*100
[1] 29
This behavior seems to be independent of what is being repeated (rep()'s
first argument)
> length(rep(1,0.29*100))
[1] 28
Also it occurs only with the 0.29.
> length(rep(1,0.291*100))
[1] 29
> for(a in seq(0,1,0.01)) {print(sum(rep(TRUE,a*100)))} #also shows correct
values in values from 0 to 1 except for 0.29.
I have confirmed that this behavior happens in more than one machine
(though I only have session info of this one)
> sessionInfo()
R version 2.15.3 (2013-03-01)
Platform: x86_64-w64-mingw32/x64 (64-bit)
locale:
[1] LC_COLLATE=Portuguese_Brazil.1252 LC_CTYPE=Portuguese_Brazil.1252
LC_MONETARY=Portuguese_Brazil.1252
[4] LC_NUMERIC=C LC_TIME=Portuguese_Brazil.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] spatstat_1.31-1 deldir_0.0-21 mgcv_1.7-22
loaded via a namespace (and not attached):
[1] grid_2.15.3 lattice_0.20-13 Matrix_1.0-11 nlme_3.1-108
tools_2.15.3
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