On Jul 2, 2009, at 7:20 AM, Bil Kleb wrote:

>  Given an array of integers, I need to delete all those
>  entries that are lower than the current array index.

>  Anything more elegant available?
> 
>  Or perhaps an alternative way to attack the problem?

On Ruby 1.9, your very first example can almost be made to work as is:

   > > a = Array.new(10) { |i| i + [-1, 0, 1][rand(3)] }
   =>  [-1, 1, 2, 4, 3, 5, 7, 7, 9, 10]
   > > a.delete_if.with_index { |e, i| e < i }
   =>  [1, 2, 4, 5, 7, 7, 9, 10]

James Edward Gray II