Ruby Array to Hash (a better way?)


#1

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


#2

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


#3

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


#4

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


#5

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


#6

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


#7

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