This page contains automated test results for code from O'Reilly's Ruby Cookbook. If this code looks interesting or useful, you might want to buy the whole book.
Inverting a Hash | ||
---|---|---|
Code | Expected | Actual |
phone_directory = { 'Alice' => '555-1212', 'Bob' => '555-1313', 'Mallory' => '111-1111' } phone_directory.invert |
{"111-1111"=>"Mallory", "555-1212"=>"Alice", "555-1313"=>"Bob"} | {"111-1111"=>"Mallory", "555-1212"=>"Alice", "555-1313"=>"Bob"} |
phone_directory = { 'Alice' => '555-1212', 'Bob' => '555-1313', 'Carol' => '555-1313', 'Mallory' => '111-1111', 'Ted' => '555-1212' } phone_directory.invert |
{"111-1111"=>"Mallory", "555-1212"=>"Ted", "555-1313"=>"Bob"} | {"111-1111"=>"Mallory", "555-1212"=>"Ted", "555-1313"=>"Bob"} |
class Hash def safe_invert new_hash = {} self.each do |k,v| if v.is_a? Array v.each { |x| new_hash.add_or_append(x, k) } else new_hash.add_or_append(v, k) end end return new_hash end def add_or_append(key, value) if has_key?(key) self[key] = [value, self[key]].flatten else self[key] = value end end end phone_directory.safe_invert |
{"111-1111"=>"Mallory", "555-1212"=>["Ted", "Alice"], | {"111-1111"=>"Mallory", "555-1212"=>["Ted", "Alice"], "555-1313"=>["Bob", "Carol"]} |
phone_directory.safe_invert.safe_invert |
{"Alice"=>"555-1212", "Mallory"=>"111-1111", "Ted"=>"555-1212", "Carol"=>"555-1313", "Bob"=>"555-1313"} | {"Alice"=>"555-1212", "Mallory"=>"111-1111", "Ted"=>"555-1212", "Carol"=>"555-1313", "Bob"=>"555-1313"} |