Forum: Ruby Ruby Array to Hash (a better way?)

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Mike H. (Guest)
on 2007-08-01 21:32
(Received via mailing list)
Hey Guys,

I want to convert an array like the following to a hash. Below is my
current code (I am assuming there is a better way).

Thanks

["foo", "bar", "foo1", "bar1","foo2", "bar2"]   convert to
{"foo"=>"bar", "foo1"=>"bar1","foo2"=>"bar2"}



My Current Code:

def array_to_hash(array)
  count = 0
  hash = Hash.new
  (array.length / 2).times do
    hash[array[count]] = array[count+1]
    count += 2
  end
  return hash
end
Marcin M. (Guest)
on 2007-08-01 21:36
(Received via mailing list)
skibud2 pisze:
> Hey Guys,
>
> I want to convert an array like the following to a hash. Below is my
> current code (I am assuming there is a better way).
>
> Thanks
>
> ["foo", "bar", "foo1", "bar1","foo2", "bar2"]   convert to
> {"foo"=>"bar", "foo1"=>"bar1","foo2"=>"bar2"}
>

given:
a = ["foo", "bar", "foo1", "bar1","foo2", "bar2"]

puts Hash[*a]

or:

require 'enumerator'
h = {}
a.each_slice(2){|k,v|h[k]=v}
puts h


lopex
Gordon T. (Guest)
on 2007-08-01 21:38
(Received via mailing list)
On Aug 1, 12:26 pm, skibud2 <removed_email_address@domain.invalid> wrote:
> Hey Guys,
>
> I want to convert an array like the following to a hash. Below is my
> current code (I am assuming there is a better way).
>
> Thanks
>
> ["foo", "bar", "foo1", "bar1","foo2", "bar2"]   convert to
> {"foo"=>"bar", "foo1"=>"bar1","foo2"=>"bar2"}

Use Hash#[]

>> Hash["foo", "bar", "foo1", "bar1","foo2", "bar2"]
=> {"foo1"=>"bar1", "foo2"=>"bar2", "foo"=>"bar"}

hth

Gordon
Kyle S. (Guest)
on 2007-08-01 23:10
(Received via mailing list)
I've been using Ruby for awhile, and I'm afraid I've never used the *
notation...

I can see that Hash[a] wouldn't work, and that Hash[*a] expands the
array out so that Hash can use it elegantly.

But what, in a general, does the * do?

Or is it just for special cases like this?

Thanks,
    Kyle
Sebastian H. (Guest)
on 2007-08-01 23:14
(Received via mailing list)
Kyle S. wrote:
> But what, in a general, does the * do?

It turns an array into a list of parameters (or, if used in a method
definition, a list of parameters into an array).


HTH,
Sebastian
unknown (Guest)
on 2007-08-01 23:15
(Received via mailing list)
Hi --

On Thu, 2 Aug 2007, Kyle S. wrote:

> I've been using Ruby for awhile, and I'm afraid I've never used the *
> notation...
>
> I can see that Hash[a] wouldn't work, and that Hash[*a] expands the
> array out so that Hash can use it elegantly.
>
> But what, in a general, does the * do?
>
> Or is it just for special cases like this?

It "un-arrays" its operand; in other words, given an array, the *
gives you a list.


David
Robert K. (Guest)
on 2007-08-02 02:01
(Received via mailing list)
On 01.08.2007 19:34, Marcin Mielżyński wrote:
>>
> a.each_slice(2){|k,v|h[k]=v}
> puts h

If you are using Enumerator anyway you can as well do

irb(main):001:0> a = ["foo", "bar", "foo1", "bar1","foo2", "bar2"]
=> ["foo", "bar", "foo1", "bar1", "foo2", "bar2"]
irb(main):002:0> a.to_enum(:each_slice, 2).inject({}) {|h,(k,v)| h[k]=v;
h}
=> {"foo1"=>"bar1", "foo2"=>"bar2", "foo"=>"bar"}
irb(main):003:0>

Kind regards

  robert
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