From 3f278de42d9486d01faabe618724cadfab698634 Mon Sep 17 00:00:00 2001
From: Bart Arendarczyk <s1924442@ed.ac.uk>
Date: Tue, 2 May 2023 14:45:13 +0100
Subject: [PATCH] Stocks can no longer go negative. Improved price update.
---
src/ac/ed/lurg/InternationalMarket.java | 2 +-
src/ac/ed/lurg/ModelConfig.java | 2 +-
src/ac/ed/lurg/country/CountryAgent.java | 75 +++++++++-------------
src/ac/ed/lurg/country/CountryManager.java | 4 ++
src/ac/ed/lurg/country/GlobalPrice.java | 71 ++++++++++++--------
src/ac/ed/lurg/types/CropType.java | 22 +++----
6 files changed, 91 insertions(+), 85 deletions(-)
diff --git a/src/ac/ed/lurg/InternationalMarket.java b/src/ac/ed/lurg/InternationalMarket.java
index 36d9bd57..2a1436f7 100644
--- a/src/ac/ed/lurg/InternationalMarket.java
+++ b/src/ac/ed/lurg/InternationalMarket.java
@@ -143,7 +143,7 @@ public class InternationalMarket {
LogWriter.println(timestep.getYear() + " Updating " + crop.getGamsName() + " prices", 2);
GlobalPrice adjustedPrice = prevPrice.createWithUpdatedMarketPrices(imports, exportsBeforeTransportLosses,
timestep, totalProduction.get(crop), true, crop.getStockToUseRatio());
- LogWriter.println( String.format("Price for %s updated from %s to %s \n", crop.getGamsName(), prevPrice, adjustedPrice), 2);
+ LogWriter.println( String.format("Price for %s updated from %s \nto %s \n", crop.getGamsName(), prevPrice, adjustedPrice), 2);
if (adjustedPrice.getStockLevel() < 0)
LogWriter.println("Global stocks are below zero" + crop.getGamsName() + ", " + timestep.getYear(), 2);
diff --git a/src/ac/ed/lurg/ModelConfig.java b/src/ac/ed/lurg/ModelConfig.java
index 9de22fae..485f730a 100755
--- a/src/ac/ed/lurg/ModelConfig.java
+++ b/src/ac/ed/lurg/ModelConfig.java
@@ -389,7 +389,7 @@ public class ModelConfig {
public static final ModelFitType DEMAND_ANIMAL_PROD_FIT = ModelFitType.findByName(getProperty("DEMAND_ANIMAL_PROD_FIT", "loglinear"));
public static final ModelFitType DEMAND_NON_ANIMAL_PROD_FIT = ModelFitType.findByName(getProperty("DEMAND_NON_ANIMAL_PROD_FIT", "loglinear"));
public static final boolean LIMIT_DEMAND_FRACTION = getBooleanProperty("LIMIT_DEMAND_FRACTION", true);
- public static final boolean DEMAND_FRACT_BY_COST = getBooleanProperty("DEMAND_FRACT_BY_COST", false);;
+ public static final boolean DEMAND_FRACT_BY_COST = getBooleanProperty("DEMAND_FRACT_BY_COST", true);;
public static final double MAX_INCOME_PROPORTION_FOOD_SPEND = getDoubleProperty("MAX_INCOME_PROPORTION_FOOD_SPEND", 0.7);
public static final double PASTURE_HARVEST_FRACTION = getDoubleProperty("PASTURE_HARVEST_FRACTION", 0.5);
diff --git a/src/ac/ed/lurg/country/CountryAgent.java b/src/ac/ed/lurg/country/CountryAgent.java
index 75c4dfd5..5f557b17 100644
--- a/src/ac/ed/lurg/country/CountryAgent.java
+++ b/src/ac/ed/lurg/country/CountryAgent.java
@@ -164,12 +164,12 @@ public class CountryAgent extends AbstractCountryAgent {
for (Map.Entry<CropType, CropUsageData> entry : previousGamsRasterOutput.getCropUsageData().entrySet()) {
CropUsageData cropUsage = entry.getValue();
CropType crop = entry.getKey();
+ GlobalPrice cropPrice = currentWorldPrices.get(crop);
double baseTrade = cropUsage.getNetImportsExpected();
double changeUp, changeDown;
// max of supply overall, needed for when imports are supplying feed and change is zero to allow for production to replace imports
- // minimum 1 so trade balance can still change when supply is 0
- double maxOfProdOrSupply = Math.max(cropUsage.getProductionExpected() + Math.max(baseTrade, 0), 1);
+ double maxOfProdOrSupply = cropUsage.getProductionExpected() + Math.max(baseTrade, 0);
if (ModelConfig.IS_CALIBRATION_RUN && currentTimestep.getTimestep() <= ModelConfig.END_FIRST_STAGE_CALIBRATION) {
changeUp = changeDown = 0;
@@ -177,24 +177,18 @@ public class CountryAgent extends AbstractCountryAgent {
changeDown = changeUp = maxOfProdOrSupply * ModelConfig.MAX_IMPORT_CHANGE;
if (crop.isImportedCrop()) {
- // Guide export level towards import level
- if (baseTrade < 0) {
- if (crop.equals(CropType.RUMINANTS)) {
- int foo = 1;
- }
- double ratio = currentWorldPrices.get(crop).getExportAdjustment(crop.getStockToUseRatio());
- baseTrade *= ratio;
- cropUsage.updateNetImports(cropUsage.getNetImportsExpected() * ratio);
- }
+ changeUp = cropPrice.getTradeChangeUp(maxOfProdOrSupply);
+ changeDown = cropPrice.getTradeChangeDown(maxOfProdOrSupply, crop.getStockToUseRatio());
- // If stock about to go negative temporarily increase import price
- if (currentWorldPrices.get(crop).isStockCritical()) {
- currentCountryPrices.get(crop).adjustImportPrice(2.0);
+ if (changeUp < 0) { // need to reduce imports to avoid negative stocks
+ baseTrade += changeUp;
+ cropUsage.updateNetImports(baseTrade);
+ changeUp = 0;
}
}
}
- if (CropType.ENERGY_CROPS.equals(crop) && baseTrade == 0) { // could apply this logic for all crops?
+ if (CropType.ENERGY_CROPS.equals(crop) && baseTrade == 0) { // need this in case we start with no global production
changeDown = changeUp = ModelConfig.MAX_IMPORT_CHANGE * currentGen2EcDemand;
}
@@ -217,7 +211,8 @@ public class CountryAgent extends AbstractCountryAgent {
importConstraints.put(crop, tradeConstraint);
}
-
+
+ // Carbon trade constraints
TradeConstraint carbonTradeConstraint;
CarbonUsageData carbonUsageData = previousGamsRasterOutput.getCarbonUsageData();
@@ -228,19 +223,14 @@ public class CountryAgent extends AbstractCountryAgent {
if (Math.abs(baseTrade) < 1e-3) { // to set initial trade when starting from zero
changeUp = changeDown = getCurrentCarbonDemand();
} else {
- double maxOfProdOrSupply = Math.max(carbonUsageData.getCarbonCredits() + Math.max(baseTrade, 0), 1);
- changeUp = changeDown = maxOfProdOrSupply * ModelConfig.MAX_IMPORT_CHANGE;
-
- // Guide export level towards import level
- if (baseTrade < 0) {
- double ratio = globalCarbonPrice.getExportAdjustment(ModelConfig.DEFAULT_STOCK_USE_RATIO);
- baseTrade *= ratio;
- carbonUsageData.updateNetImports(carbonUsageData.getNetCarbonImport() * ratio);
- }
-
- // If stock about to go negative temporarily increase import price
- if (globalCarbonPrice.isStockCritical()) {
- currentCarbonPrice.adjustImportPrice(2.0);
+ double maxOfProdOrSupply = carbonUsageData.getCarbonCredits() + Math.max(baseTrade, 0);
+ changeUp = globalCarbonPrice.getTradeChangeUp(maxOfProdOrSupply);
+ changeDown = globalCarbonPrice.getTradeChangeDown(maxOfProdOrSupply, ModelConfig.DEFAULT_STOCK_USE_RATIO);
+
+ if (changeUp < 0) { // need to reduce imports to avoid negative stocks
+ baseTrade += changeUp;
+ carbonUsageData.updateNetImports(baseTrade);
+ changeUp = 0;
}
}
@@ -250,9 +240,8 @@ public class CountryAgent extends AbstractCountryAgent {
carbonTradeConstraint = new TradeConstraint(0, 0);
}
- Map<WoodType, TradeConstraint> woodTradeConstraints = new HashMap<WoodType, TradeConstraint>();
-
// Timber import/export constraints
+ Map<WoodType, TradeConstraint> woodTradeConstraints = new HashMap<WoodType, TradeConstraint>();
Map<WoodType, WoodUsageData> woodUsageData = previousGamsRasterOutput.getWoodUsageData();
for (Map.Entry<WoodType, WoodUsageData> entry : woodUsageData.entrySet()) {
@@ -262,27 +251,21 @@ public class CountryAgent extends AbstractCountryAgent {
continue;
}
WoodUsageData woodUsage = entry.getValue();
+ GlobalPrice woodPrice = globalWoodPrices.get(woodType);
double baseTrade = woodUsage.getNetImport();
- double changeUp;
- double changeDown;
-
- double maxOfProdOrSupply = Math.max(woodUsage.getProduction() + Math.max(baseTrade, 0), 1);
+ double changeUp, changeDown;
+ double maxOfProdOrSupply = woodUsage.getProduction() + Math.max(baseTrade, 0);
if (ModelConfig.IS_CALIBRATION_RUN && currentTimestep.getTimestep() <= ModelConfig.END_FIRST_STAGE_CALIBRATION) {
changeUp = changeDown = 0.0;
} else {
- changeUp = changeDown = maxOfProdOrSupply * ModelConfig.MAX_IMPORT_CHANGE;
-
- // Guide export level towards import level
- if (baseTrade < 0) {
- double ratio = globalWoodPrices.get(woodType).getExportAdjustment(ModelConfig.DEFAULT_STOCK_USE_RATIO);
- baseTrade *= ratio;
- woodUsageData.get(woodType).updateNetImports(woodUsageData.get(woodType).getNetImport() * ratio);
- }
+ changeUp = woodPrice.getTradeChangeUp(maxOfProdOrSupply);
+ changeDown = woodPrice.getTradeChangeDown(maxOfProdOrSupply, ModelConfig.DEFAULT_STOCK_USE_RATIO);
- // If stock about to go negative temporarily increase import price
- if (globalWoodPrices.get(woodType).isStockCritical()) {
- currentWoodPrices.get(woodType).adjustImportPrice(2.0);
+ if (changeUp < 0) { // need to reduce imports to avoid negative stocks
+ baseTrade += changeUp;
+ woodUsage.updateNetImports(baseTrade);
+ changeUp = 0;
}
}
diff --git a/src/ac/ed/lurg/country/CountryManager.java b/src/ac/ed/lurg/country/CountryManager.java
index 14a5a8e6..2b537143 100644
--- a/src/ac/ed/lurg/country/CountryManager.java
+++ b/src/ac/ed/lurg/country/CountryManager.java
@@ -86,4 +86,8 @@ public class CountryManager {
return codeMap.containsKey(isoCode);
}
+ public int getCountryCount() {
+ return mapFromCompositeCountry.size();
+ }
+
}
diff --git a/src/ac/ed/lurg/country/GlobalPrice.java b/src/ac/ed/lurg/country/GlobalPrice.java
index 6c47365e..a8719fd7 100644
--- a/src/ac/ed/lurg/country/GlobalPrice.java
+++ b/src/ac/ed/lurg/country/GlobalPrice.java
@@ -19,9 +19,11 @@ public class GlobalPrice implements Serializable {
private double stockUseRatio;
private double referencePrice;
private double prevStockChange;
+ private double production;
private GlobalPrice(Timestep timestep, double exportPrice, double stockLevel, double importAmount, double exportAmountBeforeLoss,
- double transportLosses, double referencePrice, double stockUseRatio, double prevStockChange) {
+ double transportLosses, double referencePrice, double stockUseRatio, double prevStockChange,
+ double production) {
this.timestep = timestep;
this.exportPrice = exportPrice;
this.stockLevel = stockLevel;
@@ -31,12 +33,13 @@ public class GlobalPrice implements Serializable {
this.transportLosses = transportLosses;
this.referencePrice = referencePrice;
this.prevStockChange = prevStockChange;
+ this.production = production;
LogWriter.println("Created " + this, 3);
}
public static GlobalPrice createInitial(double exportPrice, double intitalStock) {
return new GlobalPrice(new Timestep(ModelConfig.START_TIMESTEP-1), exportPrice, intitalStock, Double.NaN,
- Double.NaN, Double.NaN, Double.NaN, Double.NaN, 0.0);
+ Double.NaN, Double.NaN, Double.NaN, Double.NaN, 0.0, intitalStock / 0.1);
}
public double getExportPrice(){
@@ -53,6 +56,8 @@ public class GlobalPrice implements Serializable {
double tradeBarrierMultiplier = ModelConfig.updateParameterForShocks(currentYear, "TRADE_BARRIER_MULTIPLIER");
double transportLossesRate =ModelConfig.updateParameterForShocks(currentYear, "TRANSPORT_LOSSES");
double transportCosts = ModelConfig.updateParameterForShocks(currentYear, "TRANSPORT_COST");
+
+ //transportCosts = timestep.getYear() >= 2023 ? transportCosts * 1.5 : transportCosts;
double importPrice = exportPrice * (1 + transportCosts) * (1.0 + countryTradeBarrier*tradeBarrierMultiplier) / (1.0 - transportLossesRate);
return importPrice;
@@ -89,9 +94,9 @@ public class GlobalPrice implements Serializable {
else
updatedStock = stockLevel + stockChange;
- double targetStock = (production + newImports - newExportAmountBeforeLoss) * targetStockUseRatio;
+ double targetStock = production * targetStockUseRatio;
double updatedStockUseRatio = production > 0 ? updatedStock / production : 0;
-
+
LogWriter.println(String.format(" imports %.2f, exports %.2f", newImports, newExportAmountBeforeLoss - newTransportLosses), 2);
LogWriter.println(String.format(" updatedStock %.2f, previous %.2f (last timestep %.2f), stockChange %.2f, oldDiff %.2f", updatedStock, stockLevel, stockLevel-oldDiff, stockChange, oldDiff), 2);
@@ -101,14 +106,25 @@ public class GlobalPrice implements Serializable {
adjustment = 1;
}
else if (ModelConfig.PRICE_UPDATE_METHOD.equals("StockFlow")) {
- // Sum of target stock and trade flow volume. Trying to avoid large swings in prices when stocks low
- double stockAndFlow = stockLevel + Math.max(newImports, newExportAmountBeforeLoss);
+ // Market lambda lower when the rate of change in stock is decreasing
+ // Acts as a damping mechanism to reduce price fluctuation
+ double lambda = Math.atan2(Math.abs(stockChange), Math.abs(prevStockChange)) / (0.5 * Math.PI) * ModelConfig.MARKET_LAMBDA;
+
+ // Prices decrease more slowly than they increase (20% slower according to FAO food price index)
+ if (stockChange > 0)
+ lambda *= 0.8;
+
+ LogWriter.println("lambda="+lambda);
+
+ // Adjust price based on stock change
+ adjustment = 1 - lambda * stockChange / production;
- // (1) stockChange analogous to velocity of change
- // (2) (stockChange - prevStockChange) analogous to acceleration of change
- // We need (2) to avoid large changes in prices when trade imbalance is already reducing
- adjustment = 1 - ModelConfig.MARKET_LAMBDA * (stockChange + 0.5 * (stockChange - prevStockChange)) / stockAndFlow;
+ // If below target stock and stocks not already increasing, nudge prices to increase stock.
+ if (updatedStock < targetStock & stockChange < 0) {
+ adjustment *= 1 - 0.5 * ModelConfig.MARKET_LAMBDA * (updatedStock - targetStock) / production;
+ }
}
+
else if (ModelConfig.PRICE_UPDATE_METHOD.equals("MarketImbalance")) {
double ratio = stockChange/(production-stockChange);
adjustment = Math.exp(-ratio * ModelConfig.MARKET_LAMBDA);
@@ -139,7 +155,7 @@ public class GlobalPrice implements Serializable {
double refPrice = ModelConfig.IS_CALIBRATION_RUN ? exportPrice : referencePrice; // during calibration reference price isn't fixed, but it is after that
return new GlobalPrice(thisTimeStep, newPrice, updatedStock, newImports, newExportAmountBeforeLoss,
- newTransportLosses, refPrice, updatedStockUseRatio, stockChange);
+ newTransportLosses, refPrice, updatedStockUseRatio, stockChange, production);
}
else {
LogWriter.printlnWarning(String.format("Price for not updated (still %s), as no imports and no exports for it", exportPrice));
@@ -150,7 +166,7 @@ public class GlobalPrice implements Serializable {
@Override
public String toString() {
return "GlobalPrice [timestep=" + timestep.getTimestep() + ", exportPrice=" + exportPrice + ", importAmount=" + importAmount
- + ", stockLevel=" + stockLevel + ", referencePrice=" + referencePrice + "]";
+ + ", stockLevel=" + stockLevel + ", referencePrice=" + referencePrice + ", production=" + production + "]";
}
public double getReferencePrice() {
@@ -160,31 +176,34 @@ public class GlobalPrice implements Serializable {
public double getStockChange() {
return exportAmountBeforeLoss - transportLosses - importAmount;
}
+
+ public double getProduction() {
+ return production;
+ }
public GlobalPrice createPriceAdjustedByFactor(double factor) {
return new GlobalPrice(timestep, exportPrice * factor, stockLevel, importAmount, exportAmountBeforeLoss,
- transportLosses, referencePrice, stockUseRatio, prevStockChange);
+ transportLosses, referencePrice, stockUseRatio, prevStockChange, production);
}
public void resetStock(Double stock) {
this.stockLevel = stock;
}
- public boolean isStockCritical() { // is stock projected to go below 0?
- double stockChange = exportAmountBeforeLoss - transportLosses - importAmount;
- return stockLevel + stockChange + (stockChange - prevStockChange) <= 0;
+ public double getTradeChangeUp(double maxOfProdOrSupply) {
+ // plus 5% of global production divided by number of countries in case country has 0 supply
+ maxOfProdOrSupply += 0.05 * production / CountryManager.getInstance().getCountryCount();
+ double supplyFraction = maxOfProdOrSupply / (production * 1.05);
+ // ensures stocks don't go below zero even if no exports
+ return (0.95 * stockLevel - (importAmount - getExportsAfterTransportLosses())) * supplyFraction;
}
- public double getExportAdjustment(double targetStockUseRatio) {
- double targetStockLevel = (stockLevel / stockUseRatio) * targetStockUseRatio;
- double surplus = stockLevel - targetStockLevel;
- double targetExport = exportAmountBeforeLoss
- - ModelConfig.EXPORT_ADJUSTMENT_RATE * (exportAmountBeforeLoss - importAmount)
- - ModelConfig.STOCK_ADJUSTMENT_RATE * surplus;
- targetExport = Math.max(targetExport, 0); // can't be negative
- double ratio = exportAmountBeforeLoss > 0 ? targetExport / exportAmountBeforeLoss : 1;
- return ratio;
+ public double getTradeChangeDown(double maxOfProdOrSupply, double targetStockUseRatio) {
+ // plus 5% of global production divided by number of countries in case country has 0 supply
+ maxOfProdOrSupply += 0.05 * production / CountryManager.getInstance().getCountryCount();
+ double supplyFraction = maxOfProdOrSupply / (production * 1.05);
+ // Allow exports to increase until stocks 50% above target stock level
+ return Math.max(targetStockUseRatio * production * 1.5 - stockLevel, 0) * supplyFraction;
}
-
}
\ No newline at end of file
diff --git a/src/ac/ed/lurg/types/CropType.java b/src/ac/ed/lurg/types/CropType.java
index 47a13ab1..2019fb77 100644
--- a/src/ac/ed/lurg/types/CropType.java
+++ b/src/ac/ed/lurg/types/CropType.java
@@ -11,18 +11,18 @@ import ac.ed.lurg.utils.LogWriter;
public enum CropType {
- WHEAT("WheatBarleyOats", "wheat", true, false, 9.5, ModelConfig.INITAL_PRICE_WHEAT, 0.45),
- MAIZE("MaizeMilletSorghum", "maize", true, false, 5.1, ModelConfig.INITAL_PRICE_MAIZE, 0.35),
- RICE("Rice (Paddy Equivalent)", "rice", true, false, 8.3, ModelConfig.INITAL_PRICE_RICE, 0.50),
- OILCROPS("Oilcrops", "oilcrops", true, false, 4.4, ModelConfig.INITAL_PRICE_OILCROPS, 0.25),
- PULSES("Pulses", "pulses", true, false, 10.8, ModelConfig.INITAL_PRICE_PULSES, 0.45),
- STARCHY_ROOTS("Starchy Roots", "starchyRoots", true, false, 14.3, ModelConfig.INITAL_PRICE_STARCHYROOTS, 0.10),
- ENERGY_CROPS("Energy crops", "energycrops", true, false, 5, ModelConfig.INITAL_PRICE_ENERGYCROPS, 0.2),
+ WHEAT("WheatBarleyOats", "wheat", true, false, 9.5, ModelConfig.INITAL_PRICE_WHEAT, 0.3),
+ MAIZE("MaizeMilletSorghum", "maize", true, false, 5.1, ModelConfig.INITAL_PRICE_MAIZE, 0.3),
+ RICE("Rice (Paddy Equivalent)", "rice", true, false, 8.3, ModelConfig.INITAL_PRICE_RICE, 0.3),
+ OILCROPS("Oilcrops", "oilcrops", true, false, 4.4, ModelConfig.INITAL_PRICE_OILCROPS, 0.3),
+ PULSES("Pulses", "pulses", true, false, 10.8, ModelConfig.INITAL_PRICE_PULSES, 0.3),
+ STARCHY_ROOTS("Starchy Roots", "starchyRoots", true, false, 14.3, ModelConfig.INITAL_PRICE_STARCHYROOTS, 0.3),
+ ENERGY_CROPS("Energy crops", "energycrops", true, false, 5, ModelConfig.INITAL_PRICE_ENERGYCROPS, 0.3),
SETASIDE("setaside", "setaside", false, false, 0, 0, 0),
- MONOGASTRICS("Monogastrics", "monogastrics", true, true, 3.1, ModelConfig.INITAL_PRICE_MONOGASTRICS, 0.35),
- RUMINANTS("Ruminants", "ruminants", true, true, 2.2, ModelConfig.INITAL_PRICE_RUMINANTS, 0.10),
- FRUITVEG("FruitVeg", "fruitveg", true, false, 8.9, ModelConfig.INITAL_PRICE_FRUITVEG, 0.10),
- SUGAR("Sugar", "sugar", true, false, 0.1, ModelConfig.INITAL_PRICE_SUGAR, 0.40),
+ MONOGASTRICS("Monogastrics", "monogastrics", true, true, 3.1, ModelConfig.INITAL_PRICE_MONOGASTRICS, 0.3),
+ RUMINANTS("Ruminants", "ruminants", true, true, 2.2, ModelConfig.INITAL_PRICE_RUMINANTS, 0.3),
+ FRUITVEG("FruitVeg", "fruitveg", true, false, 8.9, ModelConfig.INITAL_PRICE_FRUITVEG, 0.3),
+ SUGAR("Sugar", "sugar", true, false, 0.1, ModelConfig.INITAL_PRICE_SUGAR, 0.3),
PASTURE("pasture", "pasture", false, false, 0, 0, 0); // confusing having a land cover and a crop type. Needed here for yields (but not used for cropland area fractions).
private String faoName;
--
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