Turning a hash into an array

ruby-talk
1

While reading the archives, I found out about this cool “idiom”:

hash = Hash[*ary]

which will turn [1,2,3,4] into {1=>2, 3=>4}. Is there anything similar
to do the opposite (i.e., turn {1=>2, 3=>4} into [1,2,3,4] or
[3,4,1,2])? I can only come up with this:

ary = Hash.to_a.flatten

···

–
dave

2

In article 401169B2.7000503@zara.6.isreserved.com,

While reading the archives, I found out about this cool “idiom”:

hash = Hash[*ary]

which will turn [1,2,3,4] into {1=>2, 3=>4}. Is there anything similar
to do the opposite (i.e., turn {1=>2, 3=>4} into [1,2,3,4] or
[3,4,1,2])? I can only come up with this:

ary = Hash.to_a.flatten

Well this is something I didn’t know about till I saw Matz mention it in
another thread today:

irb(main):010:0> obj = {‘a’ => 1, ‘b’ => 2}
=> {“a”=>1, “b”=>2}
irb(main):011:0> Array(obj)
=> [[“a”, 1], [“b”, 2]]

Now you could flatten it:

irb(main):012:0> Array(obj).flatten
=> [“a”, 1, “b”, 2]

Phil

···

David Garamond lists@zara.6.isreserved.com wrote:

3

“David Garamond” lists@zara.6.isreserved.com schrieb im Newsbeitrag
news:401169B2.7000503@zara.6.isreserved.com…

While reading the archives, I found out about this cool “idiom”:

hash = Hash[*ary]

which will turn [1,2,3,4] into {1=>2, 3=>4}. Is there anything similar
to do the opposite (i.e., turn {1=>2, 3=>4} into [1,2,3,4] or
[3,4,1,2])? I can only come up with this:

ary = Hash.to_a.flatten

You can use inject if you want to save the intermediate array:

irb(main):050:0> h=Hash[1,2,3,4]
=> {1=>2, 3=>4}
irb(main):051:0> h.inject(){|arr,(key,val)| arr << key << val}
=> [1, 2, 3, 4]

Regards

robert