On Aug 26, 2011, at 10:16 AM, Joanne Demmler wrote:
Dear all,
I'm trying to rerun some data linkage exercises in R (they are
designed to be done in SPSS, SAS or STATA)
The exercise in question is to relabel the column "treat" to "1", if
"yearsep" is smaller than 1988 and columns "proc1"-"proc3" contain
the values 56.36 or 59.81.
My pathetic solution to do this in R currently looks like this:
vaslinks4$treat <- 0
Why not just?
# skip the setting to 0 step
vaslinks4$treat <- as.integer( with( vaslinks,
yearsep < 1988 &
(proc2 %in% c(56.36,59.81) |
proc3 %in% c(56.36,59.81) )
) )
Maybe, but watch out about testing for equality or set membership when
using floating point numbers.
vaslinks4$treat[vaslinks4$yearsep < 1988 && (vaslinks4$proc1 %in%
c(56.36,59.81)
|| vaslinks4$proc2 %in% c(56.36,59.81)
|| vaslinks4$proc3 %in% c(56.36,59.81))] <- 1
A doomed strategy. Don't use "&&" or "||' when working with vectors.
But I'm sure there is a more elegant solution for this, in which I
would not have to call all three columns separately.
Anyone?
Yours Joanne
Snipped SAS and Stata code.
--
David Winsemius, MD
West Hartford, CT
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