ruby collect unique elements

Question

I have some array of hashes

a = [{name:"x", long:1.0, lat:2.0}, 
     {name:"y", long:2.0, lat:3.0}, 
     {name:"z", long:1.0, lat:2.0}]

how to delete {name:"x", long:1.0, lat:2.0}, which coords are equal of last element, Other words I need to leave last (in my case: with name:"z") hash with unique coords and drop all previous element with same coords

Answer 1

Try using Array#uniq with a block:

a.uniq { |item| [item[:lat], item[:long]] }

The return value of the block is used as the value to compare for uniqueness.

It's not clear why you want "x" to be deleted and not "z", but you could achieve that with the example data set by reversing the array before calling uniq on it.