http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f
--
David Winsemius
On Apr 7, 2009, at 10:35 AM, stefan.d...@gmail.com wrote:
Hello,
I came across a strange behavior of expand.grid (or at least strange
to me).
For certain values of one of my input variables - created by seq() - I
have to use strings (e.g ==".6") to select a row of the object
created by expand.grid(), for other values numerical (e.g. ==.8) and
for some both work. Please find an example below.
#Example
x<- seq(0,1,1/10)
y <- seq(0,1,1/10)
gridd <- expand.grid(x,y )
gridd[which( gridd[,2]=="0.6" ),] #gives me the right data
gridd[which( gridd[,2]==0.6 ) ,] #gives error message
gridd[which( gridd[,2]=="0.4" ),] #gives right data
gridd[which( gridd[,2]==0.4 ),] #gives right data
gridd[which( gridd[,2]=="0.0" ),] #gives error message
gridd[which( gridd[,2]==0.0 ),] #gives me the right data
#End of Example
I also encountered this phenomenon on another version of R and on
another computer.
Has anybody an idea what this is and how to overcome it?
Best,
Stefan
Sys.getlocale()
[1] "LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United
Kingdom.1252;LC_MONETARY=English_United
Kingdom.1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252"
version
_
platform i386-pc-mingw32
arch i386
os mingw32
system i386, mingw32
status
major 2
minor 8.0
year 2008
month 10
day 20
svn rev 46754
language R
version.string R version 2.8.0 (2008-10-20)
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