I need to sort an Hash according to order of keys present in other array:
hash = { a: 23, b: 12 }
array = [:b, :a]
required_hash #=> { b: 12, a: 23 }
Is there any way to do it in single line?
4 Answers
hash = { a: 23, b: 12 }
array = [:b, :a]
array.zip(hash.values_at(*array)).to_h
#=> {:b=>12, :a=>23}
The steps:
v = hash.values_at(*array)
#=> [12, 23]
a = array.zip(v)
#=> [[:b, 12], [[:a, 23]]
a.to_h
#=> {:b=>12, :a=>23}
1 Comment
Steve Wilhelm
I personally like @Ilya's answer below
You can try something like this:
array = [:b, :a]
{ a: 23, b: 12 }.sort_by { |k, _| array.index(k) }.to_h
#=> {:b=>12, :a=>23}
Comments
If
hash = { a:23, b:12 }
array = [:b, :a]
As a one liner:
Hash[array.map{|e| [e, hash[e]]}]
As for ordering, it was some time ago, when ruby changed the implementation where the hash keys are ordered according to insert order. (Before that there was no guarantee that keys would be sorted one way or another).
4 Comments
Cary Swoveland
Good answer, but I will never understand why people say (sic), "here's a one-liner", followed by a single line of code.
Roland Mai
@CarySwoveland Personally, I do it to emphasize that Ruby is succinct and you can write a lot of things into a one liners (in comparison to C#/Java).
Jörg W Mittag
Newlines have no meaning in C♯/Java, you can always write any C♯/Java program in one line, no matter how complex, that's not a feature unique to Ruby.
Roland Mai
@JörgWMittag Yes, yes, I'm sure you know about www.ioccc.org. To me a one liner is a piece of code that is readable within a reasonable 80-120 chars length.
I do not see any sorting, I think essentially you are doing this:
hash = { a:23, b:12 }
array = [:b, :a]
res = {}
array.each { |key| res[key] = hash[key] } && res # `&& res` is just syntax sugar to return result in single line
#=> {:b=>12, :a=>23}
aandb?