From: 7stud -- <bbxx789_05ss@...>
Date: 2008-01-24T19:30:39+09:00
Subject: Re: Change a data structure

Michael Schmarck wrote:
> Hello!
> 
> I've got the following data structure, which I need to change, to
> suit further needs:
> 
> timing_given = {
>   "Performance Test of Item Access using Lists" => [
>     {"Plants" => 100, "Customers" => 50, "Total" => 150},
>     {"Plants" => 85,  "Customers" => 60, "Total" => 140},
>     {"Plants" => 111, "Customers" => 77, "Total" => 188}
>   ],
>   "Performance Test of Item Access using Advance Item Search" => [
>     {"Work List" => 17, "Total" => 42},
>     {"Work List" => 10, "Total" => 50},
>     {"Work List" => 22, "Total" => 99},
>     {"Work List" => 15, "Total" => 60}
>   ]
> }
> 
> Now I'd like to change that, so that it looks somewhat like this:
> 
> timing_wanted = {
>  "Performance Test of Item Access using Lists" => {
>    "Plants" => [100, 85, 111], "Customers" => [50, 60, 77], "Total" => 
> [150, 140, 188]
>  },
>  Performance Test of Item Access using Advance Item Search" => {
>    "Work List" => [17, 10, 22], "Bookmarks" => [30, 33, 27], "Total" => 
> [42, 50, 99]
>  }
> }
> 
> Let me explain...
> 
> I've got a hash called "timing_given", which has, right now, two keys.
> These keys have arrays as values. The elements of these arrays are again
> hashes.
> 
> Now this should be changed to match what's shown in "timing_wanted". 
> Ie.,
> create a hash, which has two keys. These keys should have hashes as 
> values
> and the values of these hashes should be arrays.
> 
> The data represent some timing measurement data. In the example I'm 
> showing,
> the Plants, Customers and Total tests have been run 3 times, 
> consecutively.
> So, first the Plants test was run, then the Customers test and then the
> Total test.
> 
> I want to collect all the Plants (etc.pp.) tests in one array. This 
> array
> should have as many elements, as there were test runs for the Plants 
> test.
> Accordingly for the other tests.
> 
> In reality, there are more tests than what I've shown. And as you can 
> see,
> there are two test "categories", called "Performance Test of Item Access
> using Lists" and "Performance Test of Item Access using Advance Item 
> Search".
> In reality, there might be more. Under these categories, there might be
> 2, 3, 4 or whatever test runs - but the number of test runs for a 
> category
> is always constant.
> 
> How would I best "mess up" that timing_given data structure, so that it
> resembles the timing_wanted structure?
> 
> Thanks a lot,
> Michael

Try this:

timing_given = {
  "Performance Test of Item Access using Lists" => [
    {"Plants" => 100, "Customers" => 50, "Total" => 150},
    {"Plants" => 85,  "Customers" => 60, "Total" => 140},
    {"Plants" => 111, "Customers" => 77, "Total" => 188}
  ],
  "Performance Test of Item Access using Advance Item Search" => [
    {"Work List" => 17, "Total" => 42},
    {"Work List" => 10, "Total" => 50},
    {"Work List" => 22, "Total" => 99},
    {"Work List" => 15, "Total" => 60}
  ]
}

timing_wanted = {}

timing_given.each do |key1, value1|
  #Make a list be the default lookup value
  #for a non-existent hash key:

  timing_wanted[key1] = Hash.new do |h, k|
    h[k] = []
  end

  value1.each do |hash|
    hash.each do |key2, value2|
      timing_wanted[key1][key2] << hash[key2]
    end
  end
end

p timing_wanted

--output:--
{"Performance Test of Item Access using Advance Item Search"=>{"Work 
List"=>[17, 10, 22, 15], "Total"=>[42, 50, 99, 60]}, "Performance Test 
of Item Access using Lists"=>{"Plants"=>[100, 85, 111], "Total"=>[150, 
140, 188], "Customers"=>[50, 60, 77]}}
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