What is the best way to convert an array to a hash in Ruby

You can also simply convert a 2D array into hash using:

1.9.3p362 :005 > a= [[1,2],[3,4]]

 => [[1, 2], [3, 4]]

1.9.3p362 :006 > h = Hash[a]

 => {1=>2, 3=>4} 

Appending to the answer but using anonymous arrays and annotating:

Hash[*("a,b,c,d".split(',').zip([1,2,3,4]).flatten)]

Taking that answer apart, starting from the inside:

• "a,b,c,d" is actually a string.
• split on commas into an array.
• zip that together with the following array.
• [1,2,3,4] is an actual array.

The intermediate result is:

[[a,1],[b,2],[c,3],[d,4]]

flatten then transforms that to:

["a",1,"b",2,"c",3,"d",4]

and then:

*["a",1,"b",2,"c",3,"d",4] unrolls that into "a",1,"b",2,"c",3,"d",4

which we can use as the arguments to the Hash[] method:

Hash[*("a,b,c,d".split(',').zip([1,2,3,4]).flatten)]

which yields:

{"a"=>1, "b"=>2, "c"=>3, "d"=>4}