Allow price to be adjusted from stock levels

src/ac/ed/lurg/InternationalMarket.java

@@ -9,34 +9,33 @@ import java.util.Map.Entry;
 
 import ac.ed.lurg.country.AbstractCountryAgent;
 import ac.ed.lurg.country.GlobalPrice;
-import ac.ed.lurg.country.StockReader;
 import ac.ed.lurg.landuse.CropUsageData;
 import ac.ed.lurg.types.CropToDoubleMap;
 import ac.ed.lurg.types.CropType;
-import ac.ed.lurg.types.Parameter;
 import ac.ed.lurg.utils.LogWriter;
 
 public class InternationalMarket {
 
 	private Map<CropType, GlobalPrice> worldPrices = new HashMap<CropType, GlobalPrice>();
-	private Map<CropType, Double> stockLevel;
 
 	public InternationalMarket() {
-		for (CropType crop : CropType.getImportedTypes())
+		//Map<CropType, Double> stockLevel = getInitialStockLevels();
+
+		for (CropType crop : CropType.getImportedTypes()) {
+			//Double stock = stockLevel.get(crop);
 			worldPrices.put(crop, GlobalPrice.createInitial(crop.getInitialPrice()));
-		
-		stockLevel = getInitialStockLevels();
+		}
 	}
 	
 	public  Map<CropType, GlobalPrice> getWorldPrices() {
 		return worldPrices;
 	}
 
-	private Map<CropType, Double> getInitialStockLevels() {
+/*	private Map<CropType, Double> getInitialStockLevels() {
 		Map<CropType, Double> initialStockLevels = new StockReader().read();
 		initialStockLevels.put(CropType.ENERGY_CROPS, 0.0);
 		return initialStockLevels;
-	}
+	} */
 
 	void determineInternationalTrade(Collection<AbstractCountryAgent> countryAgents, double gen2EcDDemand, Timestep timestep) {
 		CropToDoubleMap totalImportCommodities = new CropToDoubleMap();
@@ -69,17 +68,10 @@ public class InternationalMarket {
 			GlobalPrice prevPrice = worldPrices.get(crop);
 			double imports = totalImportCommodities.containsKey(crop) ? totalImportCommodities.get(crop) : 0.0;
 			double exportsBeforeTransportLosses = totalExportCommodities.containsKey(crop) ? totalExportCommodities.get(crop) : 0.0;
-			double previousStockLevel = stockLevel.get(crop); 
-			double transportLossRate=(!ModelConfig.SHOCKS_POSSIBLE) ? ModelConfig.TRANSPORT_LOSSES : ModelConfig.getParameter(Parameter.TRANSPORT_LOSSES, timestep.getYear());
-			GlobalPrice adjustedPrice = prevPrice.createWithUpdatedMarketPrices(imports, exportsBeforeTransportLosses, exportsBeforeTransportLosses * transportLossRate, (ModelConfig.MARKET_ADJ_PRICE), timestep, totalProduction.get(crop));
-			LogWriter.println( String.format("Price for %s updated from %s (imports amount %.1f, exports amount %.1f) to %s ",
-							crop.getGamsName(), prevPrice, imports, adjustedPrice.getExportsAfterTransportLosses(), adjustedPrice));
+			LogWriter.print("Updating " + crop.getGamsName() + " prices : ");
+			GlobalPrice adjustedPrice = prevPrice.createWithUpdatedMarketPrices(imports, exportsBeforeTransportLosses, timestep, totalProduction.get(crop));
+			LogWriter.println( String.format("Price for %s updated from %s to %s \n", crop.getGamsName(), prevPrice, adjustedPrice));
 			worldPrices.put(crop, adjustedPrice);
-			double updatedStockLevel = previousStockLevel + adjustedPrice.getStockChange();
-			stockLevel.put(crop, updatedStockLevel);
-			LogWriter.println(String.format("Global stocks for %s updated from %s to %s ", crop.getGamsName(), previousStockLevel, updatedStockLevel));
-			if (updatedStockLevel < 0)
-				LogWriter.println(String.format("Global stocks for %s is below zero ", crop.getGamsName(), previousStockLevel));
 		}
 	}
 	
@@ -89,7 +81,7 @@ public class InternationalMarket {
 			GlobalPrice priceQuantity = worldPrices.get(crop);
 			sbData.append(String.format("%d,%s", timestep.getYear(), crop.getGamsName()));
 			sbData.append(String.format(",%.1f,%.1f", priceQuantity.getImportAmount(), priceQuantity.getExportsAfterTransportLosses()));
-			sbData.append(String.format(",%.8f,%.3f", priceQuantity.getExportPrice(), stockLevel.get(crop)));
+			sbData.append(String.format(",%.8f,%.3f", priceQuantity.getExportPrice(), priceQuantity.getStockLevel()));
 
 			outputFile.write(sbData.toString());
 			outputFile.newLine();

src/ac/ed/lurg/ModelConfig.java

@@ -342,6 +342,8 @@ public class ModelConfig {
 	public static final double SUGAR_SUB_PROPORTION  = getDoubleProperty("SUGAR_SUB_PROPORTION", 0.1);
 
 	public static final double MARKET_LAMBA = getDoubleProperty("MARKET_LAMBA", 0.4); // controls international market price adjustment rate
+	public static final boolean PRICE_UPDATE_BY_MARKET_IMBALANCE = getBooleanProperty("PRICE_UPDATE_BY_MARKET_IMBALANCE", false);;
+	public static final double STOCK_TARGET_RATE = getDoubleProperty("STOCK_TARGET_RATE", 0.05);
 	public static final int DEMAND_RECALC_MAX_ITERATIONS = getIntProperty("DEMAND_RECALC_MAX_ITERATIONS", 0);  // 0 is original behaviour
 
 	public static final double POPULATION_AGGREG_LIMIT = getDoubleProperty("POPULATION_AGGREG_LIMIT", 30.0);  // in millions, smaller countries are aggregated on a regional basis
@@ -395,5 +397,5 @@ public class ModelConfig {
 	public static final double CONSTANT_PROTECTED_AREA_RATE = getDoubleProperty("CONSTANT_PROTECTED_AREA_RATE", Double.NaN);
 
 	public static final boolean USE_CRAFTY_COUNTRIES = getBooleanProperty("USE_CRAFTY_COUNTRIES", false);
-	public static final String CRAFTY_PRODUCTION_DIR = getProperty("CRAFTY_PRODUCTION_DIR", OUTPUT_DIR + File.separator + "crafty");	
+	public static final String CRAFTY_PRODUCTION_DIR = getProperty("CRAFTY_PRODUCTION_DIR", OUTPUT_DIR + File.separator + "crafty");
 }

src/ac/ed/lurg/country/GlobalPrice.java

@@ -10,21 +10,27 @@ public class GlobalPrice {
 	private double importAmount;
 	private double exportAmountBeforeLoss;
 	private double transportLosses;
+	private double stockLevel;
 
-	public GlobalPrice(double exportPrice, double importAmount, double exportAmountBeforeLoss, double transportLosses) {
+	private GlobalPrice(double exportPrice, double stockLevel, double importAmount, double exportAmountBeforeLoss, double transportLosses) {
 		this.exportPrice = exportPrice;
+		this.stockLevel = stockLevel;
 		this.importAmount = importAmount;
 		this.exportAmountBeforeLoss = exportAmountBeforeLoss;
 		this.transportLosses = transportLosses;
 	}
 	
 	public static GlobalPrice createInitial(double exportPrice) {
-		return new GlobalPrice(exportPrice, Double.NaN, Double.NaN, Double.NaN);
+		return new GlobalPrice(exportPrice, Double.NaN, Double.NaN, Double.NaN, Double.NaN);
 	}
 	
 	public double getExportPrice(){
 		return exportPrice;
 	}
+
+	public double getStockLevel(){
+		return stockLevel;
+	}
 	
 	public double getCountryImportPrice(double countryTradeBarrier, Timestep timestep) {
 
@@ -55,19 +61,46 @@ public class GlobalPrice {
 		return transportLosses;
 	}
 
-	public GlobalPrice createWithUpdatedMarketPrices(double imports, double exportsBeforeTransportLosses, double transportLosses, boolean adjustPrice, Timestep timestep, double production) {
+	public GlobalPrice createWithUpdatedMarketPrices(double imports, double exportsBeforeTransportLosses, Timestep timestep, double production) {
+
+		if (Double.isNaN(stockLevel))
+			stockLevel = ModelConfig.STOCK_TARGET_RATE * production;  // set stock initially to target level, this is pretty horrible and should really be done on construction but don't easily have production value at that point
+
+		double transportLossRate = (!ModelConfig.SHOCKS_POSSIBLE) ? ModelConfig.TRANSPORT_LOSSES : ModelConfig.getParameter(Parameter.TRANSPORT_LOSSES, timestep.getYear());
+		double transportLosses = exportsBeforeTransportLosses * transportLossRate;
 		double exportsAfterTransportLosses = exportsBeforeTransportLosses - transportLosses;
+		
 		if (imports > 0 || exportsAfterTransportLosses > 0) {
-			double ratio;
-
-			ratio = (imports-exportsAfterTransportLosses)/(imports-exportsAfterTransportLosses+production);
-			double adjustment = adjustPrice ? Math.exp(ratio * ModelConfig.MARKET_LAMBA) : 1.0;
-			//adjustment = Math.min(adjustment, 2.0);  // can only double in a time step
-			//adjustment = Math.max(adjustment, 0.5); // can only half in a time step	
-			double financialSpeculationMultiplier = (!ModelConfig.SHOCKS_POSSIBLE)? 1.0 : ModelConfig.getParameter(Parameter.FINANCIAL_SPECULATION_MULTIPLIER,timestep.getYear());
+			double updatedStock = stockLevel + exportsBeforeTransportLosses - transportLosses - imports;
+			LogWriter.println(String.format(" global stocks from %.2f to %.2f", stockLevel, updatedStock));
+			if (updatedStock < 0)
+				LogWriter.println(String.format("Global stocks are below zero"));
 			
-			return new GlobalPrice(exportPrice * adjustment *financialSpeculationMultiplier, imports, exportsBeforeTransportLosses, transportLosses);
+			double newPrice, adjustment;
+			double financialSpeculationMultiplier = (!ModelConfig.SHOCKS_POSSIBLE)? 1.0 : ModelConfig.getParameter(Parameter.FINANCIAL_SPECULATION_MULTIPLIER,timestep.getYear());
+
+			if (!ModelConfig.MARKET_ADJ_PRICE) {
+				adjustment = 1;
+			}
+			else if (ModelConfig.PRICE_UPDATE_BY_MARKET_IMBALANCE) {
+				double ratio = (imports-exportsAfterTransportLosses)/(imports-exportsAfterTransportLosses+production);
+				adjustment =  Math.exp(ratio * ModelConfig.MARKET_LAMBA);
+				LogWriter.println(String.format("Price update market imbalance: adjustment= %s, imports %.1f, exports %.1f", adjustment, imports, getExportsAfterTransportLosses()));
+			}
+			else {
+				double stockTarget = ModelConfig.STOCK_TARGET_RATE * production;
+				double ratio = (stockTarget - updatedStock) / stockTarget;
+				
+				if (Math.abs(ratio) >= 1)
+					adjustment = 10;  // default to max change
+				else
+					adjustment = 1 + ModelConfig.MARKET_LAMBA * ratio/(1 - ratio*ratio);
+				
+				LogWriter.println(String.format("Price update from stock target: adjustment= %s, ratio= %s", adjustment, ratio));
+			}
 			
+			newPrice = exportPrice * adjustment * financialSpeculationMultiplier;
+			return new GlobalPrice(newPrice, updatedStock, imports, exportsBeforeTransportLosses, transportLosses);			
 		}
 		else {
 			LogWriter.printlnError(String.format("Price for not updated (still %s), as no imports and no exports for it", exportPrice));