subset problem (reducing from six to two levels)
On Thu, Feb 05, 2009 at 01:01:59PM -0800, Ine wrote:
Hi all,
I have got a seemingly simple problem (I am an R starter) with subsetting my
data set, but cannot figure out the solution: I want to subset a data set
from six to two levels, so that all analyses are done only with these two
remaining levels.
I tried
TOTAL<-read.delim('total.csv',header=T)
SUBSET.OF.TOTAL<-subset(TOTAL, FactorX %in% c("Level1","Level2"))
attach(SUBSET.OF.TOTAL)
but R does not eliminate the remaining levels of FactorX,
One solution is to have the factors re-built after subsetting:
foo = factor(c('a','a','b','c','c'))
# unused levels persistent:
foo[foo=='a']
[1] a a Levels: a b c # but:
factor(foo[foo=='a'])
[1] a a Levels: a cu Philipp
Dr. Philipp Pagel Lehrstuhl f?r Genomorientierte Bioinformatik Technische Universit?t M?nchen Wissenschaftszentrum Weihenstephan 85350 Freising, Germany http://mips.gsf.de/staff/pagel