[R] Reorder in decreasing order

[Sverre Stausland]

reorder() is probably the best way to order the levels in a vector
without manually specifying the order. But reorder() orders by default
in an increasing order: "The levels are ordered such that the values
returned by ‘FUN’ are in increasing order."

Is there a way to do what reorder() does, but order the levels
according to a _decreasing_ order of the values?

Sverre