Fastest/One-liner way to remove duplicates (by key) in Ruby Array?

Question

What's the fastest/one-liner way to remove duplicates in an array of objects, based on a specific key:value, or a result returned from a method?

For instance, I have 20 XML Element nodes that are all the same name, but they have different "text" values, some of which are duplicates. I would like to remove the duplicates by saying "if element.text == previous_element.text, remove it". How do I do that in Ruby in the shortest amount of code?

I've seen how to do it for simple string/integer values, but not for objects.

Answer 1

Here's the standard hashy way. Note the use of ||= operator, which is a more convenient (a ||= b) way to write a = b unless a.

array.inject({}) do |hash,item|
   hash[item.text]||=item
   hash 
end.values.inspect

You can do it in a single line either.

The script needs O(n) equality checks of text strings. That's what's covered under O(n) when you see a hash.