On Mar 27, 2012, at 3:37 AM, peter dalgaard wrote:
On Mar 26, 2012, at 17:33 , David Winsemius wrote:
The usual approach to that problem is to use sapply:
x <- list()
x <- sapply(1:10, function(z) x[[z]] <- 1:z )
Yikes!
If that works, it is only by coincidence.... (The pre-assignment to
x only serves the purpose of allowing the "[["-assignment inside the
anonymous function, but the assignment is to a local copy which is
deleted on exit, and the return value is the rhs of the assignment.)
Well, maybe not by pure coincidence. There are really two rhs's and it
was because of the outer assignment of the values to 'x' that it
worked as intended. My error is in propagating the notion that
assignments to named objects inside the function will survive outside
the function.
> x <- list(); y<-list()
> y <- sapply(1:10, function(z) x[[z]] <- 1:z )
> x
list()
Please:
x <- lapply(1:10, function(z) 1:z)
or even
x <- lapply(1:10, seq_len)
Yes, I see the error of my ways. I wonder how many times I have been
in this state of sin in the past?
--
Peter Dalgaard, Professor
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd....@cbs.dk Priv: pda...@gmail.com
David Winsemius, MD
West Hartford, CT
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