Download: https://www.nuget.org/packages/ProRata.Net/

ProRata.NET

A lightweight library to quickly Pro-Rate a number across a collection.

ProRata.NET introduces an extension method to IEnumberable called ProRate which can be called on any class that implements this interface. This means that it can Pro Rate against a List containing any object type. Pro-Rating can be simple or weighted.

Simple Pro-Rate

The following is an example of a simple Pro-Rata where the number 100 is pro rated evenly across a collection of strings:

List<string> people = new List<string>();
people.Add("George");
people.Add("Sue");
people.Add("Sam");
people.Add("Simon");

var resultObj = people.ProRate(100)
                  .Calculate();

The above example will calculate 20 allocated to each string as this is an even pro rate.

Calculate Return Value

Calculate will return an instance of ProRateResult which contains a Result property that is a dictionary. The dictionary has its keys equal to items in the collection.

The following would give you the pro rate amount that was calculated for George

var George_ProRataResult = resultObj.Result["George"];

The Sum of all the results will always equal to the amount that is being prorated.

Weighted Pro-Rate

Below is an example of a weighted Pro Rate where a number is pro rated based off a weight.

In this example, the weight is calculated as the length of each persons name:

List<string> people = new List<string>();
people.Add("George");
people.Add("Sue");
people.Add("Sam");
people.Add("Simon");

var sum_Name_Length = people.sum(r=> r.length);

var resultObj = people.ProRate(100)
                  .Weight(p=> p.length / sum_Name_Length)
                  .Calculate();

The the sum of all string lengths is 17 The weight is the strings length divided by 17.

This will allocated the following to each string:

George = 35.29 (6/17 * 100)
Sue = 17.65 (3/17 * 100)
Sam = 17.65 (3/17 * 100)
Simon = 29.41 (5/17 * 100)

Rounding

It is possible to specify to what decimal place you want the function to round to. This is done using the RoundTo function. The following is an example where the function will round each installment to 3 decimal places:

var resultObj = people.ProRate(100)
                      .Weight(p=> p.length / sum_Name_Length)
                      .RoundTo(3)
                      .Calculate();

Business Case Example

The following is an exampe of how how this can be used:

Suppose we have a university which needs to work out the cost of each semester for a course. Suppose we have a Course which costs $30,000. We have 4 Semesters in this course. The number of semesters changes per course. Suppose in our code we have a course object and a Semester object. The course object contains a list of semesters. Using this framework we can do this:

var result = Course.Semesters.ProRate(30000)
                                .Calculate();

With 4 semesters we will have 7500 assigned to each semester. This is accessible as:

decimal semester1_worth = result.Result[Semester1_object];
decimal semester2_worth = result.Result[Semester2_object];
decimal semester3_worth = result.Result[Semester3_object];
decimal semester4_worth = result.Result[Semester4_object];

Now suppose we have another requirement where the worth of each semester is based off the number of units in that semester. This would be a weighted pro-rata where the number of units divided by the total units in the course would make the semester cost.

var result= Course.Semesters.ProRate(30000)
                               .Weight(s=> s.Units.Count() / Course.total_units_count)
                               .Calculate();

RhynoVDS / ProRata.NET