On Tue, 13 Oct 2009, Kaveh Vakili wrote:
Hi all,
I was wondering whether it is possible to use the lapply() function
to alter the value of the input, something in the spirit of :
a1<-runif(100)
a2<-function(i){
a1[i]<-a1[i-1]*a1[i];a1[i]
}
a3<-lapply(2:100,a2)
Something akin to a for() loop, but using the lapply() infrastructure.
I haven't been able to get rapply() to do this.
Maybe you want to check out
?Reduce
For the example above, something like
a3 <- Reduce( "*", a1, accumulate = TRUE )
HTH,
Chuck
The reason is that the "real" a2 function is a difficult function that only
needs to be evaluated if the value of a1[i-1] meets some criteria.
Thanks in advance,
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Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cbe...@tajo.ucsd.edu UC San Diego
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