Simple conditional loop

["Huso, Manuela" <manuela.huso@oregonstate.edu>]

Dear S-news,

 

I want to create a vector of 0's and 1's whose elements are conditional on the previous element.  I start with a vector with 10 elements, the first of which is a 1.  After that I want the following elements to be 1 with probability 0.94.  If any element becomes a 0, then all succeeding elements should be 0.  I wrote the following which gave me fits trying to figure out why it doesn't work.  I don't get any error messages, it just doesn't change my 'fallen' vector. 

 

fallen<-c(1,rep(0,9))
for (i in 2:10) ifelse(fallen[i-1]==1,fallen[i]<-runif(1)<0.94,fallen[i]<-0)   

 

Then I tried it in R.  It worked perfectly.  Can anyone tell me why it doesn't work in S+, please?

 

Many thanks,

 

Manuela

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Manuela Huso
Consulting Statistician
Department of Forest Science
201H Richardson Hall
Oregon State University
Corvallis, OR   97331
ph: 541.737.6232
fx: 541.737.1393