From: Robert Klemme <shortcutter@...>
Date: 2009-03-26T01:46:41+09:00
Subject: Re: creating an array by reusing code

2009/3/25 lasitha <lasitha.ranatunga@gmail.com>:

> However, this is inefficient.  We have to make 12 passes over the
> all_req collection.
> You can, instead use Enumerable#group_by:
>
> all_req.group_by {|r| r.created_at.mon }
>
> which will return a hash of items keyed by the month.  Getting counts
> from this is simply a matter of using #map.  I'll leave this as an
> exercise :)

Or create a counter Hash and loop once:

counts = Hash.new 0
all_req.each {|r| counts[r.created_at.mon] += 1}

> Now, having said all that, the most efficient way to do this is
> probably to use a group_by clause in your finder.  Again, left as an
> exercise (mostly 'cos i don't know AR :)

Yep, the database solution is probably the best.

Cheers

robert


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