From: sto.mar@...
Date: 2013-07-10T00:47:52+09:00
Subject: Re: create variables depending on counter

Am 09.07.2013 17:13, schrieb stefan heinrich:
> As an example let us say I have an Array like this:
>
> Car
> Dog
> Car
> Car
> Dog
>
> What i want to do is I want to collect all Cars in a new Array and all
> Dogs in a new Array, too.
> So I need two new Arrays to do this. With Array.uniq.length I get the
> number of my new Arrays I need.
> Is there a way to implement this that the programme counts the uniq
> elements in the array and creates variables depending on the counter.
>
> So difficult to explain. I hope anyone can help me.

Hi,

as I already said, it's not completely clear to me what you want to do.
Anyway, I believe what you need is a hash  :)

Some use cases I could imagine:

Get a list of indices for all uniq elements:

array = ['Car', 'Dog', 'Dog', 'Car', 'Dog']
indices = Hash.new {|h,k| h[k] = [] }
array.each_with_index {|element, index| indices[element] << index }
indices
   # => {"Car"=>[0, 3], "Dog"=>[1, 2, 4]}
indices['Car']
   # => [0, 3]
indices['Dog']
   # => [1, 2, 4]


Count the number of occurences:

occurences = Hash.new(0)
array.each {|element| occurences[element] += 1 }
occurences
   # => {"Car"=>2, "Dog"=>3}


Regards,
Marcus

-- 
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