Develop Reference

Fairness in Optaplanner, but with hours instead of shifts

Im having some trouble with my fairness constraint, I want to make sure employees get:
Even amount of shifts during weeks.
Even amount of shifts in total.
Basically I want to avoid that fairness is only checking weeks (so that if there's 2 extra shifts, it won't be the same two employees getting those every week, potentially)
And I want to avoid fairness checking only the total (so that maybe one employee get much more shifts one week, then none the next, but overall theyd all still get even hours)
So I tried to follow what the docs for Optaplanner said in regards to a fairness constraint, and made two constraints for that, but unlike the docs preview that uses shifts, I need mine to be estimated in hours... So now, my code:
public int accumulateFairnessInHoursPerEmployeePerWeek(Week week)
{
//System.out.println("WEEK FAIRNESS CONSTRAINT:");
int actualWorkload = 0;
int totalAssignmentsDuringWeek = 0;
for(Employee emp : getEmployees())
{
List<Assignment> assignmentsForEmployeeDuringWeek = new ArrayList<>();
for(Assignment currentAss : getAssignmentsForSpecificWeek(week))
{
if(currentAss.getEmployee() == emp)
{
assignmentsForEmployeeDuringWeek.add(currentAss);
}
}
totalAssignmentsDuringWeek += getDurationForAssignments(assignmentsForEmployeeDuringWeek)/3600;
actualWorkload += (int) Math.pow(getDurationForAssignments(assignmentsForEmployeeDuringWeek)/3600, 2);
//System.out.println(emp.getName() + " has " + getDurationForAssignments(assignmentsForEmployeeDuringWeek)/3600 + " hours. Score: " + actualWorkload + " total: " + actualWorkload + " " + ass.getShift().getStartDate());
}
int idealWorkLoad = (int) Math.pow(totalAssignmentsDuringWeek, 2)/getEmployees().size();
//System.out.println("IDEAL: " + idealWorkLoad + " ACTUAL: " + actualWorkload + " FAIRNESS: " + (actualWorkload -idealWorkLoad));
return (actualWorkload - idealWorkLoad);
}
public int accumulateFairnessInHoursPerEmployeeInTotal()
{
System.out.println("TOTAL FAIRNESS CONSTRAINT:");
int actualWorkload = 0;
int totalDuration = 0;
for(Employee emp : getEmployees())
{
List<Assignment> assignmentsForEmployee = new ArrayList<>();
for(Assignment currentAss : getAssignments())
{
if(currentAss.getEmployee() == emp)
{
assignmentsForEmployee.add(currentAss);
}
}
totalDuration += getDurationForAssignments(assignmentsForEmployee)/3600;
actualWorkload += (int) Math.pow(getDurationForAssignments(assignmentsForEmployee)/3600, 2);
System.out.println(emp.getName() + " has " + getDurationForAssignments(assignmentsForEmployee)/3600 + " hours. Score: " + actualWorkload);
}
int idealWorkLoad = (int) Math.pow(totalDuration, 2)/getEmployees().size();
System.out.println("IDEAL: " + idealWorkLoad + " ACTUAL: " + actualWorkload + " FAIRNESS: " + (actualWorkload - idealWorkLoad));
return (actualWorkload - idealWorkLoad);
}
And here's the drools:
rule "EvenWorkloadPerEmployeeTotal"
when
$service : Service
(
$service.accumulateFairnessInHoursPerEmployeeInTotal() != 0
)
then
if(isDroolActivated(kcontext.getRule().getName(), $service))
{
setDroolRating(scoreHolder, kcontext, $service.getDroolStrength(drools), $service.accumulateFairnessInHoursPerEmployeeInTotal());
}
end
rule "EvenWorkloadPerEmployeePerWeek"
when
$week : Week()
$service : Service
(
$service.accumulateFairnessInHoursPerEmployeePerWeek($week) != 0
)
then
if(isDroolActivated(kcontext.getRule().getName(), $service))
{
setDroolRating(scoreHolder, kcontext, $service.getDroolStrength(drools), $service.accumulateFairnessInHoursPerEmployeePerWeek($week));
}
end
It seemingly works most of the time, especially in smaller datasets... However, when I use a bigger dataset...
This is my results:
A has 76.0 hours. Score: 5776
B has 118.0 hours. Score: 19700
C has 76.0 hours. Score: 25476
D has 83.0 hours. Score: 32365
E has 88.0 hours. Score: 40109
F has 72.0 hours. Score: 45293
G has 68.0 hours. Score: 49917
H has 64.0 hours. Score: 54013
I has 96.0 hours. Score: 63229
J has 94.0 hours. Score: 72065
K has 92.0 hours. Score: 80529
L has 67.0 hours. Score: 85018
M has 98.0 hours. Score: 94622
N has 95.0 hours. Score: 103647
O has 101.0 hours. Score: 113848
P has 90.0 hours. Score: 121948
Q has 93.0 hours. Score: 130597
R has 108.0 hours. Score: 142261
S has 124.0 hours. Score: 157637
T has 116.0 hours. Score: 171093
IDEAL: 157560 ACTUAL: 171093 FAIRNESS: 13533
The numbers go pretty high...
And I doubt anyone finds it fair that G and H gets only 64-68 hours, but S must work for 124 hours
I'm wondering if theres another/better way to estimate fairness when using time instead of shifts to calculate fairness?
EDIT: Probably worth noting that I tried with days as well, but the numbers seemed far too small using those, it was like it didn't care much for a single day too much on one employee compared to another.
I'm using these constraints at the same time, but not with other constraints involved

Take a look at the tennis example, specifically this line.
rule "fairAssignmentCountPerTeam"
when
accumulate(
$t : Team()
and accumulate(
TeamAssignment(team == $t);
$assignmentCount : count() // This could be a sum of hours too
);
$result : loadBalance($assignmentCount)
)
then
scoreHolder.addMediumConstraintMatch(kcontext, - (int) $result.getMeanDeviationSquaredSumRootMillis());
end

Rising tuition cost after ten years

Suppose that the tuition for a university is $10,000 this year and increases 5% every year. In one year, the tuition will be $10,500. Write a program that computes the tuition in ten years and the total cost of four years' worth of tuition after the tenth year.
I can calculate the tenth year tuition easily enough. What has me stumped is how to add the unique tuition values at years 11, 12, 13 and 14.
double Fee = 10000;
double Year = 1;
double TotalFee;
double Rate = 5;
double TotalCost = 15000 + 15500 + 16000 + 16500;
System.out.println("Year " + " Total Fee ");
System.out.println();
while (Year <= 14) {
TotalFee = Fee + ((Fee * ((Year * Rate) - Rate)) / 100);
System.out.println(Year + " " + " "+ TotalFee);`
Year++;
}
System.out.println("Total cost tuition of 4 years starting 10 years from now is " + TotalCost);
The last while loop is my attempt at adding the 4 years. How could I pull out the unique values of TotalCost at iterations 11 to 14 and add them?

Since you want to increase the amount 5% every year, instead of having rate = 5
You should have rate = 1.05.
With the rate as 1.05 you can do this
FeeAtYear1 = 10000*1.05^0 = 10000
FeeAtYear2 = 10000*1.05^1 = 10500
FeeAtYear3 = 10000*1.05^2 = 11025
FeeAtYear4 = 10000*1.05^3 = 11576.25
...
FeeAtYear10 = 10000*1.05^9 = ~16288.95
You don't even need a while loop.
TotalCost = 10000 *1.05^10 + 10000 *1.05^11 + 10000 *1.05^12 + 10000 *1.05^13;

Trying to make a while loop work properly

I'm making a program that calculates the population for a year given the start year (2011) and increases the population by 1.2% every year. The population for 2011 is 7.000 (I'm using decimals, instead of billions). Here is the working part of my code
package src;
import java.util.Scanner;
import java.text.DecimalFormat;
public class Demographics {
public static void main(String[] args) {
Scanner user_input= new Scanner(System.in);
//Part 1
System.out.println("===--- Part 1 ---===");
System.out.println("Population in 2011: 7.000");
System.out.print("What is the desired year? ( > 2011) ");
int startYear = 2011;
int endYear = user_input.nextInt();
while (endYear <= startYear){
System.out.println("Invalid end year.");
System.out.print("What is the desired year? ( > 2011) ");
endYear = user_input.nextInt();
break;
}
double t = 0.012;
double nbr = (endYear - startYear);
double pStart = 7.000;
double pEnd = pStart * Math.exp(nbr * t);
DecimalFormat nf = new DecimalFormat("#.000");
System.out.println("Population in " + endYear + ":(nf.format(pEnd)));
//Part 2
System.out.println("===--- Part 2 ---===");
System.out.print("What is the target population? ( > 7.000) ");
double pTarget = user_input.nextDouble();
while (pTarget <= pStart){
System.out.println("Invalid target population.");
System.out.print("What is the target population? ( > 7.000) ");
pTarget = user_input.nextDouble();
break;
}
while (pStart < pTarget){
startYear++;
pStart = pStart + (pStart * 0.012);
System.out.println("Population in " + startYear + ": " + nf.format((pStart)));
}
}
}
Part 1 of my code calculates the population of a year when the user enters it, then part 2 shows the calculations of how many years it will take when a user enters a population to get to that point.
Here is the code that doesn't work
//Part 3
System.out.println("===--- Part 3 ---===");
t = 1.2;
pStart = 7.000;
pEnd = pStart * Math.exp(nbr * t);
while (pStart < pTarget){
startYear++;
pEnd = pStart + (pStart * 0.012);
if (pEnd >= pStart * 2 ){
System.out.println("Population in " + startYear + ": " + nf.format((pEnd)) + " Population growth rate " + ": " + (t / 2));
}else{
System.out.println("Population in " + startYear + ": " + nf.format((pEnd)) + " Population growth rate " + ": " + t);
}
}
Currently when i have part 3 in my code it does an infinite loop without multiplying the population. What I'm trying to do in part 3 is pretty much the same thing in part 2, but in part 3 it will display the population growth rate (t) and divide it by 2 every time the population doubles. For example:
Population in 2019 : 7.705 ; population growth rate : 1.2%
Population in 2020 : 7.798 ; population growth rate : 1.2%
Population in 2021 : 7.892 ; population growth rate : 1.2%
...
Population in 2068 : 13.873 ; population growth rate : 1.2%
Population in 2069 : 14.040 ; population growth rate : 0.6%
Anyone have any ideas on how to achieve this?

if you have problems in the loop the reason is in the condition!
while (pStart < pTarget){
so to end this code, inside the loop one of this situation has to happen:(according with your condition)
A)pStart should increase in value
B)pTarget should decrement in value
C)a "break;" have to occur
in your code you increase: startYear and pEnd, but this are not the condition to close the loop according with your condition. (i write it before:A,B,C)
1) also startYear are not re initialize it before the loop, and start already at a high value. you have to add bedore the loop:
startYear = 2011;
2) you should as far as possible to create new variables for the segment 3, is not to have problems like the one just described, is to be clear about what you are doing.
my advice for part three is this:
(Considering that I have no clear what I wanted to do reading your code, you have to cange it and make it good for you)
System.out.println("===--- Part 3 ---===");
t = 1.2;
startYear = 2011; // I add it
double pEveryYear = 7000;
while (pEveryYear < pTarget){
startYear++;
pEveryYear = pEveryYear + (pEveryYear * 0.012);
if (pEveryYear >= pTarget ){ // this condition cange only the print in the console
System.out.println("Population in " + startYear + ": " + nf.format((pEveryYear)) + " Population growth rate " + ": " + (t / 2));
break; // if you write it before the system.out you can't read it in the console.
}else{
System.out.println("Population in " + startYear + ": " + nf.format((pEveryYear)) + " Population growth rate " + ": " + t);
}
}
}
this the console output for input like "8000":
===--- Part 3 ---===
Population in 2012: 7084.000 Population growth rate : 1.2
Population in 2013: 7169.008 Population growth rate : 1.2
Population in 2014: 7255.036 Population growth rate : 1.2
Population in 2015: 7342.097 Population growth rate : 1.2
Population in 2016: 7430.202 Population growth rate : 1.2
Population in 2017: 7519.364 Population growth rate : 1.2
Population in 2018: 7609.596 Population growth rate : 1.2
Population in 2019: 7700.912 Population growth rate : 1.2
Population in 2020: 7793.323 Population growth rate : 1.2
Population in 2021: 7886.842 Population growth rate : 1.2
Population in 2022: 7981.485 Population growth rate : 1.2
Population in 2023: 8077.262 Population growth rate : 0.6

It seems you have two variables in the while loop that you try to compare however these do not actually get updated while iterating in the while loop. So after every iteration within the loop, the while condition just stays true.
See the last few lines below for a minor change to your part 3 code :
System.out.println("===--- Part 3 ---===");
t = 1.2;
pStart = 7.000;
pEnd = pStart * Math.exp(nbr * t);
while (pStart < pTarget){
startYear++;
pEnd = pStart + (pStart * 0.012);
if (pEnd >= pStart * 2 ){
System.out.println("Population in " + startYear + ": " + nf.format((pEnd)) + " Population growth rate " + ": " + (t / 2));
} else {
System.out.println("Population in " + startYear + ": " + nf.format((pEnd)) + " Population growth rate " + ": " + t);
}
pStart = startYear; // <-- NEW, you can probably use pStart instead of startYear in this code
}

The only missing thing I see in your code is that you are not updating pStart every time you go through the loop. This will not only make your loop infinite but it's also doing a wrong calculation every time except the first iteration. I added only one line from your code:
System.out.println("===--- Part 3 ---===");
t = 1.2;
pStart = 7.000;
pEnd = pStart * Math.exp(nbr * t);
while (pStart < pTarget){
startYear++;
pEnd = pStart + (pStart * 0.012);
if (pEnd >= pStart * 2 ){
System.out.println("Population in " + startYear + ": " + nf.format((pEnd)) + " Population growth rate " + ": " + (t / 2));
}else{
System.out.println("Population in " + startYear + ": " + nf.format((pEnd)) + " Population growth rate " + ": " + t);
}
pStart = pEnd;
}

Electricity/Energy Bill Calculator: Java

I am having issues figuring out exactly what is wrong with this little Electricity/Energy calculator used to calculate computer energy costs.
I'd appreciate any help.
Program:
import java.util.Scanner;
public class ElectricityCalculations {
public static void main (String [] args) {
Scanner scnr = new Scanner(System.in);
double usageHoursPerDay = 0; // Hours computer is on per day
double usageDaysPerWeek = 0; // Days computer is used per week
double usageWeeksPerYear = 0; // Weeks computer is used per year
double wattsPerHour = 0; // Watts used by computer per hour
final double COST_PER_KWH = 0.145; // Prices of power per kilowatt hour
final double LBS_CO2_PER_KWH = 0.58815; // Pounds of CO2 generated per KWH
double usageHoursPerYear = 0; // Amount of hours on per year
double usageWattHoursPerYear = 0; // Amount of watt hours consumed per year
double usageKWHPerYear = 0; // Amount of KWH used in a year
double costPerYear = 0; // Total cost per year
double lbsCO2PerYear = 0; // Total amount of CO2 in pounds released per year
// Input Values
System.out.println("How many hours is your computer on per day?");
usageHoursPerDay = scnr.nextDouble();
System.out.println("How many days per week is your computer used?");
usageDaysPerWeek = scnr.nextDouble();
System.out.println("How many weeks per year is your computer used?");
usageWeeksPerYear = scnr.nextDouble();
System.out.println("How many watts per hour does your computer use? (Suggestive value for desktop: 100, laptop: 30).");
wattsPerHour = scnr.nextDouble();
// Calculations
usageHoursPerYear = usageHoursPerDay * 365;
usageWattHoursPerYear = wattsPerHour * 8760; // 8760 is the number of hours in a year
usageKWHPerYear = usageWattHoursPerYear / 1000;
costPerYear = usageKWHPerYear * COST_PER_KWH;
lbsCO2PerYear = LBS_CO2_PER_KWH * usageKWHPerYear;
// Printing Energy Audits
System.out.println("Computer Energy Audit");
System.out.println("You use your computer for " + usageHoursPerYear + " hours per year.");
System.out.println("It will use " + usageWattHoursPerYear + " KWH/year.");
System.out.println("Whih will cost " + costPerYear + "$/year for electricity.");
System.out.println("Generating that electricity will produce " + lbsCO2PerYear + " lbs of CO2 pollution.");
return;
}
}
Inputs:
8 hours/day
5 days/week
50 weeks/year
100 watts/hour
My (wrong output):
Computer Energy Audit:
You use your computer for 2920.0 hours per year.
It will use 876000.0 KWH/year.
Whih will cost 127.02$/year for electricity.
Generating that electricity will produce 515.2194 lbs of CO2 pollution.
Correct Output:
Computer Energy Audit:
You use your computer for 2000.0 hours per year.
It will use 200.0 KWH/year.
Which will cost 28.999999999999996 $/year for electricity.
Generating that electricity will produce 117.63 lbs of CO2 pollution.

You take in the number of days per week and weeks per year as input, but forget to use them in your calculations. Also, instead of printing KWH, you are displaying the variable storing Watt Hours.
// Calculations
usageHoursPerYear = usageHoursPerDay * usageDaysPerWeek * usageWeeksPerYear; //calculate based on time used, not 365 days in the year
usageWattHoursPerYear = wattsPerHour * usageHoursPerYear; //use variable from above line
usageKWHPerYear = usageWattHoursPerYear / 1000;
costPerYear = usageKWHPerYear * COST_PER_KWH;
lbsCO2PerYear = LBS_CO2_PER_KWH * usageKWHPerYear;
// Printing Energy Audits
System.out.println("Computer Energy Audit");
System.out.println("You use your computer for " + usageHoursPerYear + " hours per year.");
System.out.println("It will use " + usageKWHPerYear + " KWH/year."); //changed to correct variable
System.out.println("Whih will cost " + costPerYear + "$/year for electricity.");
System.out.println("Generating that electricity will produce " + lbsCO2PerYear + " lbs of CO2 pollution.");

Monthly Asset Depreciation

I am writing a desktop application which will be used to calculate the monthly depreciation and Accumulation of an asset.
The accumulation is based on the number of months the user specifies.
therefore if the user specified 12 months, it should accumulate over those months.
Also the user should be able to view the accumulation value for for every month so far it is in the specified number of months. e.g if i select January it should give me the accumulated value for January and so on......
CHALLENGES : first challenge is getting the accumulation values for all the user specified months 2nd one is how to link this concept with my j form and my database since the codes i have works but how to fuse it into my program is a problem.
Depreciation Method: Straight line
below is a sample code
private void getAccumulation() {
try {
for (int row = 0; row <= 5; row++) {
double Cost_Of_Acquisition = 2000;
double Estimated_Residual_Value = 250;
int Estimated_Useful_Life = 5;
int depreciationMethod = 1;
System.out.println(" acquisition cost of asset = " + (int) Cost_Of_Acquisition);
System.out.println(" salvage value = " + (int) Estimated_Residual_Value);
System.out.println(" number of months = " + Estimated_Useful_Life);
System.out.println(" depreciation method = " + depreciationMethod);
for (int y = 1; y <= 5; y++) {
switch (depreciationMethod) {
case 1:
System.out.println(" straight line depreciation ");
double StraightLineDepreciation = ((Cost_Of_Acquisition - Estimated_Residual_Value) / Estimated_Useful_Life);
double AccumulatedDeprecaitionSL = (StraightLineDepreciation * y);
System.out.println("Asset number " + "1" + " uses straight line depreciation");
System.out.println(" depreciation charge for asset number " + "1" + " in month " + y + "=" + StraightLineDepreciation);
System.out.println("accumulated depreciation is " + AccumulatedDeprecaitionSL);
break;
case 2:
System.out.println(" sum of months digits depreciation ");
int SumofMonths = (0);
break;
}
}
}
}
}