fac2num.factor(x, numeric.levels, coerce = TRUE)
"factor"
.
x
. If numeric levels are not specified and
levels(x)
can be
coerced to numeric values, these values are used levels. If numeric
levels are not specified,
levels(x)
cannot be coerced to numeric and
coerce is T the values `1:length(levels(x))' are used. Otherwise an
error is generated.
The numeric levels are matched with the order of
levels(x)
. The
order of
levels(x)
determined internally by S-PLUS (typically as
sort(unique(x))
, and may not
correspond to the order of appearance in the factor. For example, a
factor with the levels "-" and "+", has
levels(x)
of c("+","-"). The
numeric levels must be supplied in the corresponding order. However, if the
factor is an ordered factor, with "-" < "+", this order is preserved
by S-PLUS. See the example below.
f <- factor(rep(c("+","0","-"), 5)) ff <- ordered(rep(c("+","0","-"), 5), c("-","0","+")) fac2num(f) fac2num(ff) fac2num(f, num = c( -5, 0, 5)) fac2num(ff, num = c( -5, 0, 5))