From: Robert Klemme <shortcutter@...>
Date: 2007-06-02T18:00:35+09:00
Subject: Re: Array index of first bigger number...

On 02.06.2007 09:30, Josselin wrote:
> Is there a simple function (I solve it w a loop.. C-minded) to find the 
> index of the first bigger element in an array
> 
> limit mini is first_element ,  if item < last_element
> item =  -2.23
> anArray = [0.0, 2.0, 5.0, 10.0, 15.0, 25.0]      first_bigger_element = 
> 0.0 index 0
> 
> item = 2.85
> anArray = [0.0, 2.0, 5.0, 10.0, 15.0, 25.0]      first_bigger_element = 
> 5.0  index 2
> 
> item = 12.55
> anArray = [0.0, 2.0, 5.0, 10.0, 15.0, 25.0]      first_bigger_element = 
> 15.0 index 4
> 
> limit maxi is last_element ,  if item > last_element
> item = 36.59
> anArray = [0.0, 2.0, 5.0, 10.0, 15.0, 25.0]      first_bigger_element = 
> 25.0 index 5
> 
> can it be writtent in just one line or a loop is unavoidable ?

Yes, it can.  Just use Enumerator.

irb(main):001:0> anArray = [0.0, 2.0, 5.0, 10.0, 15.0, 25.0]
=> [0.0, 2.0, 5.0, 10.0, 15.0, 25.0]

irb(main):007:0> anArray.to_enum(:each_with_index).find {|n,i| n > 30}
=> nil
irb(main):008:0> anArray.to_enum(:each_with_index).find {|n,i| n > 10}
=> [15.0, 4]
irb(main):009:0> anArray.to_enum(:each_with_index).find {|n,i| n > -2.23}
=> [0.0, 0]
irb(main):010:0> val, idx = anArray.to_enum(:each_with_index).find 
{|n,i| n > -2.23}
=> [0.0, 0]
irb(main):011:0> val
=> 0.0
irb(main):012:0> idx
=> 0

This also has the advantage of having to traverse the array just once 
vs. the solution Stefano presented.

Kind regards

	robert