Wacek Kusnierczyk wrote:
>
>
> there's one more curiosity about factors, in particular, ordered factors:
>
> ord <- as.ordered(nums); ord
> # [1] 0.300000000000000 0.3 0.3
> 0.300000000000000
> # Levels: 0.300000000000000 < 0.3 < 0.3 < 0.300000000000000
>
> ord[1] < ord[4]
> # TRUE
> ord[1] == ord[4]
> # TRUE
>
as a corollary, the warning printed when comparing elements of a factor
is misleading:
f = factor(1:2)
f[1] < f[2]
# [1] NA
# Warning message:
# In Ops.factor(f[1], f[2]) : < not meaningful for factors
g = as.ordered(f)
is.factor(g)
# TRUE
g[1] < g[2]
# TRUE
< *is* meaningful for factors, though not for unordered ones. the
warning is generated in Ops.factor, src/library/base/all.R:7162, and
with my limited knowledge of the r internals i can't judge how easy it
is to fix the problem.
vQ
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