find_value.rb

def find_value(key, hash)
  result = hash
  key.split('.').each do |segment|
    segment = segment.to_i if segment =~ /\d+/
    result = result[segment]
    return unless result
  end
  result
end

# find_value('foo.0.bar, {'foo' => [{'bar' => 'hi!'}]})
#   => 'hi!'