Question

Given a json array:

[{ "x":"5", "y":"20" },{ "x":"6", "y":"10" },{ "x":"50", "y":"5" }]

I’d like to find argmax(x), such that I can do puts argmax(arr, :arg => "x").y and get 5. How can I elegantly implement this in Ruby?

Edit: Clarified a bit. The idea is that you can specify the field of an element in a list that you want to maximize and the method will return the maximizing element.

Answer 1

I think you want Enumerable#max_by. To get y like you’re saying, it would be:

arr.max_by {|hash| hash['x']}['y']

(Well, actually, you’ll want the numbers to be numbers instead of strings, since ’50’ sorts lower than ‘6’. But I think you get the idea. You can to_i or do whatever processing you need in the block to get the “real” value to sort by.)