From: James Gray <james@...>
Date: 2009-07-02T21:47:15+09:00
Subject: Re: delete_if_with_index or delete_at(array) in 1.8.6?

On Jul 2, 2009, at 7:45 AM, Robert Klemme wrote:

> 2009/7/2 Bil Kleb <Bil.Kleb@nasa.gov>:
>> Hi,
>>
>> Given an array of integers, I need to delete all those
>> entries that are lower than the current array index.
>>
>> I first thought of the non-existent,
>>
>>  array.delete_if_with_index{ |e,i| e < i }
>>
>> then,
>>
>>  remove_indices = []
>>  array.each_with_index{ |e,i| remove_indices << i if e < i }
>>  array.delete_at( remove_indices )
>>
>> or the same, but with a fictious inject_with_index,
>>
>>  remove_indices = inject_with_index([]){|acc,e,i| acc << i if e < i }
>>  array.delete_at( remove_indices )
>>
>> and finally the 1.9 possibility,
>>
>>  array.map_with_index!{ |e,i| e < i ? nil : e }.compact!
>>
>> before compromising with
>>
>>  array = (0...array.size).zip(array).map{ |i,e| e < i ? nil :  
>> e }.compact
>>
>> Anything more elegant available?
>>
>> Or perhaps an alternative way to attack the problem?
>
> irb(main):010:0> a = %w{foo bar baz}
> => ["foo", "bar", "baz"]
> irb(main):011:0> current = 1
> => 1
> irb(main):012:0> a.slice! 0...current
> => ["foo"]
> irb(main):013:0> a
> => ["bar", "baz"]

You need to reread what Bil was asking for.  ;)

James Edward Gray II