Factor Codes
Usage
codes(x)
codes(x) <- value
Description
This (generic) function returns a numeric coding of a
factor. It can also be used to assign to a factor using the coded
form.Value
For an ordered factor, it returns the internal coding (1 for
the lowest group, 2 for the second lowest, etc.). For an unordered
factor, an alphabetical ordering of the levels is assumed, i.e the
level that is coded 1 is the one whose name is sorted first according
to the prevailing collating sequence.Note
The behaviour for unordered factors is dubious, but compatible
with S version 3. To get the internal coding of a factor, use
as.integer. Note in particular that the codes may not be
the same in different language locales because of collating
differences.See Also
unclass is very similar if applied to factors;
factor, levels, nlevels.Examples
codes(rep(factor(c(20,10)),3))
x <- gl(3,5)
codes(x)[3] <- 2
x
data(esoph)
( ag <- esoph$alcgp[12:1] )
codes(ag)
codes(factor(1:10)) # BEWARE!