source: src/main/java/bargainingchips/utilityfunctions/UF_PeakedFlatCurvePriceGaussianQuantity.java@ 341

package bargainingchips.utilityfunctions;


import bargainingchips.Bundle;
import bargainingchips.BundleBuilder;
import bargainingchips.Chip;
import bargainingchips.ChipIssueValue;
import bargainingchips.ChipIssueValueBuilder;
//import bargainingchips.utilityfunctions.helperMethods;
import bargainingchips.wishlist.WishList;
import bargainingchips.wishlist.WishListBuilder;

/**
 * 
 * This utility function inputs {@link wishList} (i.e., quantity of each desired {@link Chip}), and price per each 
 * {@link Chip} as curves, flattened at peak. 
 * For quantity, the buyer may accept, with degrees of satisfaction, offered quantity around the peak, which is 
 * determined by the deviation from the peak per each {@link Chip}. It is in a Guassian form. 
 * For the price, the buyer would designate the 2 points, so that they determine the left peaked flat part and the 
 * right downward curve of prices per each {@link Chip}. The prices could be in integer or real format, determined 
 * by type T[] (i.e, `Integer[]' or `Double[]', etc). Actually, the second point determines the buyer's budget for 
 * the {@link Chip} (i.e., RV, the reservation value), and the flat part determines AV (the aspiration value). 
 * It is worth to mention that this function considers the importance of issues (i.e., for price, quantity, etc.) 
 * as well as the importance of Chips (i.e., colors) with respect to each other.
 *  
 * 
 * @author Faria Nassiri-Mofakham
 *
 */

public class UF_PeakedFlatCurvePriceGaussianQuantity<T> implements UtilityFunction {
        // T for the type of `price' data points

        private WishList wishlist;                                              // the exact wished quantity per each Chip
        // Other parts of the buyer's preferences are assigned with desirability degrees of a variety of prices and quantities per each Chip. 
        private ChipIssueValue<Integer> qtyDeviation;   // sigma_c. A symmetric deviation considered for quantities less than or more than the exact qty per chip.
        private ChipIssueValue<T[]> flatCurvePrice;     // list of `2' data points of type T determining the price curve
        private ChipIssueValue<Double> uFlatCurve;              // utility in jumping from flat to curve at the first data point
        private ChipIssueValue<Double> lambdaC;                 // importance of each Chip (i.e, color)
        private double lambdaP,lambdaQ;                                 // importance of issues (i.e., price, quantity, etc)


        public UF_PeakedFlatCurvePriceGaussianQuantity(WishList w, ChipIssueValue<T[]> price, ChipIssueValue<Double> uPrice, ChipIssueValue<Integer> qtyDev, ChipIssueValue<Double> lc, double lp, double lq)
        {
                wishlist=w;
                qtyDeviation=qtyDev;
                flatCurvePrice=price;
                uFlatCurve=uPrice;
                lambdaC=lc; 
                lambdaP=lp; 
                lambdaQ=lq;
        }

        @Override
        public Double getUtility(Bundle b) 
        {
                double sumWeightedPrice = 0.0;
                double sumWeightedQty = 0.0;

                if (b!=null)
                {                       
                        for (Chip c : wishlist)
                        {
                                int desiredQ = wishlist.getQuantity(c);
                                T[] desiredP = flatCurvePrice.getUnitValue(c);
                                if (desiredP.length > 2) 
                                        throw new IllegalStateException("\n\n[Warning] UF_PeakedFlatCurvePriceAndGaussianQuantity::getUtility(Bundle). Input only 2 price data points! "+ desiredP);
                                Double uPrice = uFlatCurve.getUnitValue(c);
                                Double importanceC= lambdaC.getUnitValue(c);
                                int devC= qtyDeviation.getUnitValue(c);

                                Integer offeredQ = b.getQuantity(c);
                                if (offeredQ == null)
                                        offeredQ = 0;
                                Double offeredP= b.getUnitPrice(c);

                                sumWeightedPrice += importanceC * flatCurve(desiredP, uPrice, offeredP);
                                sumWeightedQty += importanceC / (devC * 2 * Math.sqrt(Math.PI)) * Math.pow(Math.E, -0.5 * Math.pow((offeredQ - desiredQ)/devC, 2));
                        }
                        double u = lambdaP * sumWeightedPrice + lambdaQ * sumWeightedQty;                                                               
                        return ( (u>1) ? 1 : ( (u<0) ? 0 : u) );
                }
                return 0.0;
        }

        /**
         * @param input parameter (e.g., an offered price per a {@link Chip}, 
         *                and `n' data points of type T (e.g., as of Double[], Integer[], etc).
         * 
         * @return Bezier value of rank `n' for the offered parameter.
         **/
        private double flatCurve(T[] desired, Double uDesired, Double offered)  
        {
                Double data[] = (Double[]) desired; 
                double fc = ( (offered <= data[0]) ? 1.0 : ( (offered > data[1]) ? 0.0 : uDesired * (offered - data[1]) / (data[0]-data[1]) ));
                return ( (fc>1) ? 1 : (fc<0) ? 0 : fc);
        }
        
        /**
         * @return an String list of values assigned to a single variable, e.g. list of quantities or prices of a {@link Chip}
         **/
        private String writeT(ChipIssueValue<T[]> t)
        {
                String s = "{";
                T[] j;
                if (t!=null) 
                {
                        for (Chip c: t)
                        {
                                s += " " + c.toString() + "={";
                                j = t.getUnitValue(c);
                                for (int k=0; k<j.length; k++)
                                        s += j[k].toString()+((k<j.length-1) ? ", " : "");
                                s += "}";
                        }       
                }
                s += " }";
                return s;
        }
        
        @Override
        public String toString()
        {       
                return this.getClass().getSimpleName() + ": WishList " + wishlist + ": FlatCurvePrice "+ writeT(flatCurvePrice)+ ": uFlatCurvePrice" + uFlatCurve + ": QtyDeviations "+ qtyDeviation + ": Colors' weights "+ lambdaC + ": Issue Price's weight "+ lambdaP + ": Issue Quantity's weight " + lambdaQ;
        }

        public static void main(String[] args) 
        {
                WishList wishlist = new WishListBuilder().addWish("Green", 4).addWish("Yellow", 6).addWish("Orange", 40).build();
                ChipIssueValue<Double[]> prices = new ChipIssueValueBuilder<Double[]>().addIssue("Green", new Double[] {3.0, 4.8}).addIssue("Yellow", new Double[] {5.0, 8.0}).addIssue("Orange", new Double[] {1.0, 2.5}).build();
                ChipIssueValue<Double> uPrices = new ChipIssueValueBuilder<Double>().addIssue("Green", 1.0).addIssue("Yellow", 0.8).addIssue("Orange", 0.75).build();
                ChipIssueValue<Integer> deviations = new ChipIssueValueBuilder<Integer>().addIssue("Green", 1).addIssue("Yellow", 1).addIssue("Orange", 10).build();
                ChipIssueValue<Double> wC = new ChipIssueValueBuilder<Double>().addIssue("Green", 0.5).addIssue("Yellow", 0.3).addIssue("Orange", 0.2).build();
                double wP = 0.6;
                double wQ = 0.4;

                UF_PeakedFlatCurvePriceGaussianQuantity<Double> u = new UF_PeakedFlatCurvePriceGaussianQuantity<Double> (wishlist, prices, uPrices, deviations, wC, wP, wQ);
                System.out.println(u);

                Bundle offer = new BundleBuilder()
                                .addStack("Green", 2.0, 3)
                                .addStack("Yellow", 5.0, 4)
                                .addStack("Orange", 1.0, 17)
//---                           
//                              .addStack("Green", 3.0, 4)              //should give utility 1.0 in weighted additive
//                              .addStack("Yellow", 5.0, 6)
//                              .addStack("Orange", 1.0, 40)
//---                           
//                              .addStack("Green", 10.0, 1)             //should give utility 0.0 in weighted additive
//                              .addStack("Yellow", 10.0, 1)
//                              .addStack("Orange", 10.0, 1)    
//---
//                              .addStack("Red", 1.0, 6)
//                              .addStack("Green", 3.0, 15)
//                              .addStack("Purple", 0.10, 10)                           
                                .build();
                System.out.println(u.getUtility(offer));
        }
}