Question

I have a Ruby array containing some string values. I need to:

1. Find all elements that match some predicate
2. Run the matching elements through a transformation
3. Return the results as an array

Right now my solution looks like this:

def example
  matchingLines = @lines.select{ |line| ... }
  results = matchingLines.map{ |line| ... }
  return results.uniq.sort
end

Is there an Array or Enumerable method that combines select and map into a single logical statement?

Answer 1

I usually use map and compact together along with my selection criteria as a postfix if. compact gets rid of the nils.

jruby-1.5.0 > [1,1,1,2,3,4].map{|n| n*3 if n==1}    
 => [3, 3, 3, nil, nil, nil] 


jruby-1.5.0 > [1,1,1,2,3,4].map{|n| n*3 if n==1}.compact
 => [3, 3, 3]