On Jan 5, 2012, at 12:56 AM, Bert Gunter wrote:
David!
...
It means the author either doesn't know the 'sample' function, or
wants you
to understand how to use 'rbinom', or that's just the way she thinks.
Could someone help? Thanks so much,
X1<-c("A","B")[rbinom(n,1,0.6)+1]
X2<-c("C","D")[rbinom(n,1,0.1)+1]
C.f.
X1<-sample( c("A","B"), n, prob= c(0.6, 0.4))
X2<-sample( c("C","D"), n, prob= c(0.6 ,0.4))
... are wrong for n>1 !
e.g.
X1<-sample( c("A","B"), 5, prob= c(0.6, 0.4))
Error in sample(c("A", "B"), 5, prob = c(0.6, 0.4)) :
cannot take a sample larger than the population when 'replace =
FALSE'
The perils of untested code. Thanks, Bert.
## You need to add the replace=TRUE argument
X1<-sample( c("A","B"), 5, prob= c(0.6, 0.4),replace=TRUE)
X1
[1] "A" "A" "B" "A" "B"
Cheers,
Bert
It mean index the vector as 1's and 2's (1st and 2nd item in list)
rather than 0's and 1's because R indices start at 1, not 0.
Sorry for the blank message.
--
David Winsemius, MD
West Hartford, CT
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--
Bert Gunter
Genentech Nonclinical Biostatistics
Internal Contact Info:
Phone: 467-7374
Website:
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
David Winsemius, MD
West Hartford, CT
______________________________________________
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.
