[LRUG] Sorting a hash by value

[James Adam]

It seems like the consensus is: get your data from the hash into am array of data structures with an attribute containing only the time, and then use Enumerable’s #sort for free.



— James


On Tuesday, 17 June 2014 at 17:32, George Drummond wrote:

> My solution
>  
> #######
>  
> require 'ostruct'
>  
> collection = {
> "ami-c3c73c7f"=>"tn-example 1980-09-12T17:53:25Z",
> "ami-600925fe"=>"sns-example 1983-01-05T16:21:08Z",
> "ami-131f1007"=>"dk-example 2005-01-27T23:03:01Z",
> "ami-98d4ddef"=>"tn-example 2002-10-27T11:52:26Z",
> "ami-fe6af742"=>"sns-example 1998-11-22T09:54:51Z",
> "ami-09966e45"=>"dk-example 1993-01-09T13:23:45Z",
> "ami-44e6ee6a"=>"tn-example 2013-12-23T20:52:28Z",
> "ami-cbf7f1a9"=>"sns-example 1979-09-09T07:15:47Z",
> "ami-fcd2e7ac"=>"dk-example 2007-09-02T18:34:05Z"
> }
>  
> collection_hash = collection.map do |id, value|  
> type, timestamp = value.split(' ')
>  
> OpenStruct.new(
> id: id,
> type: type,
> timestamp: Time.new(timestamp)
> )
> end
>  
> collection_hash.select { |item| item.type == 'sns-example' }.sort_by(&:timestamp)
>  
> #######
>  
>  
>  
> On Tue, Jun 17, 2014 at 10:16 PM, Gerhard Lazu <gerhard at lazu.co.uk (mailto:gerhard at lazu.co.uk)> wrote:
> > I really like Tom's approach, I'm somewhat expanding on it: https://gist.github.com/gerhard/7203f3bb51d1ad59c886
> >  
> >  
> > Twitter (http://twitter.com/#!/gerhardlazu) Github (https://github.com/gerhard) Blog (http://gerhard.lazu.co.uk/)  
> >  
> > On Tue, Jun 17, 2014 at 11:46 AM, Stephen Nelson-Smith <sanelson at gmail.com (mailto:sanelson at gmail.com)> wrote:
> > > I have a hash that looks like this:
> > >  
> > > {"ami-c3c73c7f"=>"tn-example 1980-09-12T17:53:25Z",
> > > "ami-600925fe"=>"sns-example 1983-01-05T16:21:08Z",
> > > "ami-131f1007"=>"dk-example 2005-01-27T23:03:01Z",
> > > "ami-98d4ddef"=>"tn-example 2002-10-27T11:52:26Z",
> > > "ami-fe6af742"=>"sns-example 1998-11-22T09:54:51Z",
> > > "ami-09966e45"=>"dk-example 1993-01-09T13:23:45Z",
> > > "ami-44e6ee6a"=>"tn-example 2013-12-23T20:52:28Z",
> > > "ami-cbf7f1a9"=>"sns-example 1979-09-09T07:15:47Z",
> > > "ami-fcd2e7ac"=>"dk-example 2007-09-02T18:34:05Z"}
> > >  
> > > I want to filter this hash by value and return them in sorted date order. The implementation I have just seems ugly:  
> > >  
> > > catalogue.select {|id, name| name.match /sns-example/ }.sort { |id, name| name[1] <=> id[1] }
> > > => [["ami-a65e21cc", "sns-example 2011-10-03T11:15:49Z"],
> > > ["ami-9a401c41", "sns-example 1983-09-22T15:26:00Z"],
> > > ["ami-9f9ae4d8", "sns-example 1971-03-06T03:58:52Z"]]
> > >  
> > >  
> > >  
> > > I don't like the way sort takes my hash and makes it into an array of tuples... and I'd really like it to return an array of single key/value hashes...  
> > >  
> > > Also, is there a more elegant way to perform the filter/search?
> > >  
> > > S.
> > >  
> > > --  
> > > Stephen Nelson-Smith
> > > Technical Director
> > > Atalanta Systems Ltd
> > > www.atalanta-systems.com (http://www.atalanta-systems.com)  
> > > _______________________________________________
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> > > Chat at lists.lrug.org (mailto:Chat at lists.lrug.org)
> > > http://lists.lrug.org/listinfo.cgi/chat-lrug.org
> >  
> >  
> >  
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>  
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