## Generated by Codox

# Propeller 0.3.2

Downsampling the Training Data =

Downsampling is a very simple way to improve the efficiency of your evolutionary runs. It might allow for deeper evolutionary searches and a greater success rate.

Using Downsampled selection with propeller is easy:

Set the :parent-selection argument to whichever selection strategy you would like, and set the :downsample? argument to true as follows:

    lein run -m propeller.problems.simple-regression :parent-selection :lexicase :downsample? true <required downsampling args here>

The number of evaluations is held constant when comparing to a full training set run, so set the :max-generations to a number of generations that you would have gone to using a full sample.

## Downsample Functions

In this repository, you have access to 3 different downsampling functions. These are the methods used to take a down-sample from the entire training set.

To use them, add the argument `:ds-function` followed by which function you would like to us

The list is - `:case-maxmin` - This is the method used for informed down-sampled lexicase selection - `:case-maxmin-auto` - This method automatically determines the downsample size - `:case-rand`- Random Sampling

### Using `:case-maxmin`:

In order to use regular informed down-sampled selection, you must specify a few things: - `:downsample-rate`- This is the $r$ parameter: what proportion of the full sample should be in the down-sample $\in 0,1$ - `:ds-parent-rate` - This is the $\rho$ parameter: what proportion of parents are used to evaluate case distances $\in 0,1$ - `:ds-parent-gens` - This is the $k$ parameter: How many generations in between parent evaluations for distances $\in {1,2,3, \dots}$

### Using `:case-maxmin-auto`:

In order to use automatic informed down-sampled selection, you must specify a few things: - `:case-delta`- This is the $\Delta$ parameter: How close can the farthest case be from its closest case before we stop adding to the down-sample - `:ids-type` - Either `:elite` or `:solved` - Specifies whether we are using elite/not-elite or solved/not-solved as our binary-fication of case solve vectors. - `:ds-parent-rate` - This is the $\rho$ parameter: what proportion of parents are used to evaluate case distances $\in 0,1$ - `:ds-parent-gens` - This is the $k$ parameter: How many generations in between parent evaluations for distances $\in {1,2,3, \dots}$

### Using `:case-rand`:

In order to use regular randomly down-sampled selection, you must specify a few things: - `:downsample-rate`- This is the $r$ parameter: what proportion of the full sample should be in the down-sample $\in 0,1$

Here’s an example of running informed downsampled lexicase selection with $r=0.1$, $\rho=0.01$ and $k=100$ on the simple classification problem:

    lein run -m propeller.problems.simple-classification :parent-selection :lexicase :downsample? true :ds-function :case-maxmin :downsample-rate 0.1 :max-generations 300 :ds-parent-rate 0.01 :ds-parent-gens 100