On Mon, Jun 1, 2015 at 7:03 AM, Gm <[email protected]> wrote:
> Thank you all.
>
> Paul, I end up doing this:
>
> sorted_by_second_value = Hash[hash.sort_by { |_, v| v[1] }]
> sorted_by_second_value.to_a.reverse.to_h
>
Here you're converting an array (hash.sort_by { |_, v| v[1] }) to a hash (
Hash[...]) then back to an array (.to_a) then reversing and then turning
back into a hash (.to_h).
Assuming you don't need the intermediate results, you can skip a couple of
those by just doing,
Hash[hash.sort_by { |_, v| v[1] }.reverse]
or,
hash.sort_by { |_, v| v[1] }.reverse.to_h # if you prefer .to_h
There's an interesting stackoverflow analysis on ways of descending order
sorts in Ruby. Summary: sort_by + reverse is the fastest, slightly ahead of
the -v hack (fewer ops presumably).
http://stackoverflow.com/a/2651028/683947
Paul
> Thanks.
>
> On Friday, May 29, 2015 at 6:14:53 PM UTC-3, Paul Makepeace wrote:
>>
>> sorted_by_second_value = Hash[hash.sort_by
>> <http://ruby-doc.org/core-2.2.2/Enumerable.html#method-i-sort_by> { |_,
>> v| v[1] }]
>>
>> For those saying ruby hashes are unordered:
>> http://ruby-doc.org/core-2.2.2/Hash.html
>>
>> Hashes enumerate their values in the order that the corresponding keys
>> were inserted.
>>
>>
>> sorted_by_second_value
>> .map { |_, v| v[1] }
>> => [74, 75, 84, 99, 100]
>>
>> Paul
>>
>>
>> On Fri, May 29, 2015 at 6:24 AM, Gm <[email protected]> wrote:
>>
>>> Hi, I have this hash:
>>>
>>> hash = { 4049=>[4133, 100], 5814=>[4075, 84], 382543=>[4064, 74],
>>> 382544=>[4065, 99], 382545=>[4066, 75] }
>>>
>>> I need to sort (DESC) this hash by the second item of array.
>>> Example: 100, 84, 74, 99, 75
>>>
>>> How can I solve this problem ? I'm using sort method but can't work it
>>> out.
>>>
>>> Thanks.
>>>
>>>
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