From: Robert Klemme <shortcutter@...>
Date: 2008-08-13T01:57:33+09:00
Subject: Re: Exiting .each early

On 12.08.2008 18:51, Myrddin Emrys wrote:
> I want to return part of a sorted array efficiently. The built in
> iterators will search the entire array, but since I know it's sorted, I
> only need to collect the items up until they stop being in range.
> However, its pretty wasteful to keep iterating after they start to fall
> out of range...
> 
> How do I break a .each (or .collect, .reject, etc) early?

Exactly with break. :-)

irb(main):001:0> (1..10).each {|i| p i; break if i > 5}
1
2
3
4
5
6
=> nil

> Is there a simple way to do this? A rather complex solution would be to
> create a routine to find the index where the transition from valid to
> invalid occurred, and slice the array to that index... but just being
> able to iterate over half of the items (rather than all) would be
> efficient enough for me at this point.

I rather suggest to use binary search.  There is a library in RAA that 
does it.  Maybe there's also a gem.

Kind regards

	robert