From: "David A. Black" <dblack@...>
Date: 2009-02-14T00:21:08+09:00
Subject: Re: How to retrive first 10 items from hash in ruby?

Hi --

On Sat, 14 Feb 2009, Robert Klemme wrote:

> 2009/2/13 Bertram Scharpf <lists@bertram-scharpf.de>:
>> Hi,
>>
>> Am Freitag, 13. Feb 2009, 22:02:31 +0900 schrieb David A. Black:
>>> On Fri, 13 Feb 2009, Bertram Scharpf wrote:
>>>> Am Freitag, 13. Feb 2009, 21:08:19 +0900 schrieb Dave Baldwin:
>>>>> On 13 Feb 2009, at 11:04, Vikas Gholap wrote:
>>>>>
>>>>>> I want to retrieve first 10 items(key value pairs) from given hash{}
>>>>>>
>>>>> ary = hashTable.sort {|a,b| -1*(a[1]<=>b[1])}
>>>>>
>>>> As ary is only of temporary use, you don't need to create another
>>>> array ary[0,10]. I suggest:
>>>>
>>>>  10.times { puts "Key: %s ==> %s" % e.shift }
>>>
>>> Do you mean ary.shift?
>>
>> Arrgh. Of course.
>>
>> The code may still be improved: Omit the multiplication by -1 in
>> the sort block.
>>
>>  ary = hashTable.sort { |a,b| a[1]<=>b[1] }
>>  10.times { puts "Key: %s ==> %s" % ary.pop }
>
> Did we have these already?
>
> p hash_table.sort_by {|k,v| -v}.first(10)
> p hash_table.sort_by {|k,v| v}.last(10).reverse

I think the original split between the sort and the puts was because
the main question was about sort, and the puts was just to examine the
results.


David

-- 
David A. Black / Ruby Power and Light, LLC
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