If all components are different (and no NA
s), the ranks are well
defined, with values in seq_len(x)
. With some values equal
(called ???ties???), argument ties.method
determines the result at
the corresponding indices. The "first"
method results in a
permutation with increasing values at each index set of ties. The
"random"
method puts these in random order whereas the
default, "average"
, replaces them by their mean, and
"max"
and "min"
replaces them by their maximum
and minimum respectively, the latter being the typical sports
ranking.
NA values are never considered to be equal: for na.last = TRUE
and na.last = FALSE
they are given distinct ranks in the order
in which they occur in x
.