Class: MecsEnergy

Inherits:
ActiveRecord::Base
  • Object
show all
Defined in:
lib/earth/industry/mecs_energy.rb

Constant Summary collapse

FUELS = 
[:electricity, :residual_fuel_oil, :distillate_fuel_oil,
:natural_gas, :lpg_and_ngl, :coal, :coke_and_breeze, :other_fuel]

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.find_by_naics_code(code) ⇒ Object

Find the first record whose naics_code matches code and that has valid fuel ratios. If no record found chop off the last character of code and try again, and so on.



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# File 'lib/earth/industry/mecs_energy.rb', line 33

def self.find_by_naics_code(code)
  find_by_naics_code_and_census_region_number(code, nil)
end

.find_by_naics_code_and_census_region_number(code, number, original_number = number) ⇒ Object

Find the first record whose census_region_number matches number, whose naics_code matches code, and that has valid fuel ratios. If none found and we know census region number, try looking nationwide If none found and looking nationwide, chop off the last character of code and try again looking in census region And so on



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# File 'lib/earth/industry/mecs_energy.rb', line 41

def self.find_by_naics_code_and_census_region_number(code, number, original_number = number)
  if code.blank?
    record = nil
  else
    code = Industry.format_naics_code code
    candidate = where(:census_region_number => number, :naics_code => code).first
    
    if candidate.try(:fuel_ratios).present?
      record = candidate
    elsif number.present?
      record = find_by_naics_code_and_census_region_number(code, nil, original_number)
    else
      record = find_by_naics_code_and_census_region_number(code[0..-2], original_number)
    end
  end
  record
end

Instance Method Details

#fuel_ratios ⇒ Object 



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# File 'lib/earth/industry/mecs_energy.rb', line 59

def fuel_ratios
  # Don't return a ratio if reported total energy was withheld
  if energy.to_f > 0
    # Calculate the sum of all fuels and note if any were withheld
    withheld = 0
    fuels_sum = MecsEnergy::FUELS.inject(0) do |sum, fuel|
      (value = send("#{fuel}")).nil? ? withheld = 1 : sum += value
      sum
    end
    
    # If energy > sum of all fuels and some fuels were withheld, calculate fuel ratios as fraction of energy
    # and attribute the disparity between energy and sum of all fuels to the dirtiest fuel that was withheld
    if energy > fuels_sum and withheld == 1
      ratios = MecsEnergy::FUELS.inject({}) do |r, fuel|
        fuel_use = send("#{fuel}")
        r[fuel] = fuel_use.present? ? fuel_use / energy : nil
        r
      end
      
      dirtiest_withheld = ([:coal, :other_fuel, :coke_and_breeze, :residual_fuel_oil, :distillate_fuel_oil, :lpg_and_ngl, :natural_gas] & ratios.select{|k,v| v.nil?}.keys).first
      ratios[dirtiest_withheld] = (energy - fuels_sum) / energy
      ratios.delete_if{ |fuel, ratio| ratio.to_f == 0.0 }
    # Otherwise calculate ratios as fraction of sum of all fuels, skipping any fuels that were withheld
    else
      ratios = MecsEnergy::FUELS.inject({}) do |r, fuel|
        fuel_use = send("#{fuel}")
        r[fuel] = fuel_use / fuels_sum if fuel_use.to_f > 0
        r
      end
      ratios.keys.any? ? ratios : nil
    end
  end
end