From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-11-30T01:40:44+09:00
Subject: Re: Help sorting an array

On Mon, Nov 29, 2010 at 4:47 PM, Jim Burgess <jack.zelig@gmail.com> wrote:
> Hi,
>
> I have an array consisting of "Event" objects, and string elements which
> contain the names of months.
> It looks like this:
> [#<Event:0x4d4cf78>, #<Event:0x4d4d470>, "MARCH", #<Event:0x4d4dc08>,
> #<Event:0x4d4e100>, "FEBRUARY", #<Event:0x4d4e898>,"JANUARY"]
>
> Currently the events precede the months they are ordered to.
>
> Is there any way to reverse this so that the months precede the
> events?
> Like this:
> ["MARCH", #<Event:0x4d4cf78>, #<Event:0x4d4d470>,
> "FEBRUARY",#<Event:0x4d4dc08>, #<Event:0x4d4e100>, "JANUARY",
> #<Event:0x4d4e898>]
>
> I have been scouring the documentation for ages and have also googled
> everything I can think of (e.g. Array#split) to try and find a solution,
> but with no luck.
>
> Can anyone point me in the right direction.
> I am grateful for any help.
>
> --
> Posted via http://www.ruby-forum.com/.
>
>


Borrowing from ActiveSupport's Array#split (I modified it to keep the
token on which we split as part of the previous group, and also to
remove the last group if it's empty):

irb(main):093:0> Event = Struct.new :id
=> Event
irb(main):094:0> a = [Event[1], Event[2], "MARCH", Event[3], Event[4],
"FEBRUARY", Event[5], "JANUARY"]
=> [#<struct Event id=1>, #<struct Event id=2>, "MARCH", #<struct
Event id=3>, #<struct Event id=4>, "FEBRUARY", #<struct Event id=5>,
"JANUARY"]
irb(main):095:0> class Array
irb(main):096:1>   def split(&block)
irb(main):097:2>     res = inject([[]]) do |results, element|
irb(main):098:3*       if block.call(element)
irb(main):099:4>         results.last << element
irb(main):100:4>         results << []
irb(main):101:4>       else
irb(main):102:4*         results.last << element
irb(main):103:4>       end
irb(main):104:3>       results
irb(main):105:3>     end
irb(main):106:2>     res.pop if res.last.empty?
irb(main):107:2>     res
irb(main):108:2>   end
irb(main):109:1> end
=> nil
irb(main):111:0> a.split {|o| o.kind_of? String}.each {|m| el = m.pop;
m.unshift el}.flatten
=> ["MARCH", #<struct Event id=1>, #<struct Event id=2>, "FEBRUARY",
#<struct Event id=3>, #<struct Event id=4>, "JANUARY", #<struct Event
id=5>]


Jesus.