A Wavelet-based Encoding for Neuroevolution

The code in this repository implements the Wavelet-based Encoding as proposed in our conference paper: A Wavelet-based Encoding for Neuroevolution ( http://dx.doi.org/10.1145/2908812.2908905), which appeared at GECCO'16.

Installation

Quick instructions for installation.

# Get WBE
git clone git@github.com:sjoerdvansteenkiste/WBE.git
# Install
cd WBE
pip install -r requirements.txt
pip install .

Usage

To evolve any neural network using the Wavelet-based Encoding take the following steps:

1. Determine the level of compression l.
2. Construct a dictionary structure containing all weight-tensor dimensions, which outlines the structure of the phenotoype, e.g. structure = {'L1': {'W': (12, 4, 6, 8), 'bias': (12, 14, 10)}, 'L2': {'theta': 8}}

• Ensure each tensor dim is divisible by 2^l (pad by increasing the dim in tensor_dim if necessary).
• Pass on the dimension that ensures maximal spatial correlation in the network weights i.e. for an input matrix of dimension h x mn that receives flatted pixel input of an m x n image, use h x m x n instead.

3. Compute the number of approximation wavelet coefficients to be evolved using encoding_dimensionality(structure, l).
4. Choose the wavelet-basis function to use, and compute the corresponding polyphase filter coefficients poly. See wavelet_functions.py for some pre-implemented filters.

• Use lattice_structure to compute wavelet basis function from an arbitrary set of parameters (which can be evolved alongside the wavelet coefficients).

5. Use decode(chromosome, poly, structure, l) to decode the approximation wavelet coefficients into a list of weight tensors of the specified dimension.

See examples/genes_to_weights.py for an example.