def fc_hash
  fcs = Hash.new
  self.forecasts.each do |fc|
    fcs[fc.name] = fc.data
  end
  fcs
end

Forecast = Struct.new(:name,:data)
forecasts = [Forecast.new('bob',1),Forecast.new('mary',2)]
Hash[forecasts.map{|forecast| [forecast.name,forecast.data]}]
# => {"mary"=>2,"bob"=>1}