What's the fastest way in Ruby to get the first enumerable element for which a block returns true?

ruby arrays enumerable
Nathan Long picture Nathan Long · Mar 19, 2012 · Viewed 16.3k times · Source

What's the fastest way in Ruby to get the first enumerable element for which a block returns true?

For example:

arr = [12, 88, 107, 500]
arr.select {|num| num > 100 }.first  # => 107

I'd like to do this without running through the entire array, as select will, since I only need the first match.

I know I could do an each and break on success, but I thought there was a native method for doing this; I just haven't found it in the documentation.

Answer

Holger Just picture Holger Just · Mar 19, 2012

Several core ruby classes, including Array and Hash include the Enumerable module which provides many useful methods to work with these enumerations.

This module provides the find or detect methods which do exactly what you want to achieve:

arr = [12, 88, 107, 500]
arr.find { |num| num > 100 } # => 107

Both method names are synonyms to each other and do exactly the same.

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