Write your own utility function

Task

Write a function that can be used as the utility argument in scenario.optimizer.

Preparation

You need R.

Doing it

There are requirements on the arguments and on the output.

Arguments

The first argument should expect a random portfolio object.  It is traditionally called rp.

The second argument should be called scenarios.

There can be as many additional arguments as you like, with or without default values.

Output

The output needs to be a numeric vector that is as long as the input random portfolio object.  (And obviously each value in the output should be for the corresponding random portfolio.)

 Body

All of the utility functions in pprobeSup use the valuation function from Portfolio Probe, and hence the scenarios argument must be a matrix or a three-dimensional array of prices.  But there is no reason that valuation has to be used and hence no reason that scenarios must look anything like an array of prices.

Explanation

scenario.optimizer presents the utility function a set of portfolios.  It then uses the result to select the portfolio in the set with the best utility.

Further details

pputil.multomega is an example of combining utilities from multiple times.  pputil.valueWt is an example of allowing scenarios to have different importances.

See also

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