

   OOrrddeerriinngg PPeerrmmuuttaattiioonn

        order(...)

   AArrgguummeennttss::

        ...: a sequence of vectors, all of the same length.

   DDeessccrriippttiioonn::

        `order' returns a permutation which rearranges its
        first argument into ascending order, breaking ties by
        further arguments.

   DDeettaaiillss::

        In the case of ties in the first vector, values in the
        second are used to break the ties.  If the values are
        still tied, values in the later arguments are used to
        break the tie (see 1st example).

        `NA' values are treated as greater than any other val-
        ues so that permutations returned by `order' move `NA'
        values to the top end of the array.

   SSeeee AAllssoo::

        `sort' and `rank'.

   EExxaammpplleess::

        (ii <- order(x <- c(1,1,3:1,1:4,3), y <- c(9,9:1), z <-c(2,1:9)))
        ## 6  5  2  1  7  4 10  8  3  9
        rbind(x,y,z)[,ii] # shows the reordering (ties via 2nd & 3rd arg)

        ## rearrange matched vectors so that the first is in ascending order
        x <- c(5:1, 6:8, 12:9)
        y <- (x - 5)^2
        o <- order(x)
        rbind(x[o], y[o])

