"The ugly thing on top that covers up what's missing" A library for Deep Learning ensembles, with a tooolkit for running experiments, based on Keras.

Usage:

Experiments are described in a common YAML format, and each network structure is in serialised Keras format.

Supports saving results to MongoDB for analysis later on.

In bin/ you will find 3 files:

• mlp.py: takes an experiment description and runs it as a single network. Ignores all ensemble directives.

• ensemble.py: takes an experiment description and runs it as an ensemble.

• distilled_ensemble.py: takes an experiment description and runs it as an ensemble, and then distils the ensemble into a single network.

In examples/ there are a few ready-cooked models that you can look at.

• Install keras from the fork
• Clone this repo
• In examples/ there are a few working examples of experiments:
  • Download the needed dataset from here and save it to the correct location (or change the location in the example)
• Run bin/mlp.py for single network experiments, bin/ensemble.py for ensemble experiments

Datasets are saved in the .npz format, with three files in a directory:

• train.npz: the training set
• valid.npz: the validation set
• test.npz: the test set Each of these files is a serialised dictionary {x: numpy.array, y: numpy.array} where x is the input data and y is the expected classification output.

This is the file given as an argument to mlp.py, ensemble.py or distilled_ensemble.py. It is a yaml description of the experiment. Here is an example experiment file:

---
## MLP Parameters ##
dataset: /local/mnist_th/
pickled: false
model_file: mnist.model
optimizer:
  class_name: WAME
  config:
    lr: 0.001
    decay: 1e-4
n_epochs: 100 #max number of training epochs
batch_size: 128
cost_function: categorical_crossentropy
shuffle_dataset: true

## Ensemble Parameters ##
ensemble_size: 10
method: !AdaBoostM1 { }
resample_size: 60000

The parameters are as follows:

network parameters

• dataset: the location of the dataset. If in "pickle" format, this is a file; if in "npz" format, this is a directory.
• pickled: true if the dataset is in "pickle" format, false if "npz". Default is false.
• model_file: the location of the serialised Keras model description.
• optimizer: the SGD optimization method. See separate section for description.
• n_epochs: the number of training epochs.
• batch_size: the number of samples to use at each iteration
• cost_function: the cost function to use. Any string accepted by Keras works.
• shuffle_dataset: whether to shuffle the dataset at each epoch.

ensemble parameters

• ensemble_size: the number of ensemble members to create.
• method: a class describing the ensemble method. See separate section for description.
• resample_size: if the ensemble method uses resampling, this is the size of the set to be resampled at each round.

optimizer subparameters

• class_name: a string that Keras can deserialise to a learning algorithm. Note that our Keras fork includes WAME, presented at ESANN
• config:
  • lr: either a float for a fixed learning rate, or a dictionary of (epoch, rate) pairs
  • decay: learning rate decay

ensemble methods

• Bagging: Bagging
• AdaBoostM1: AdaBoost.M1
• DIB: Deep Incremental Boosting. Parameters are as follows.
  • n_epochs_after_first: The number of epochs for which to train from the second round onwards
  • freeze_old_layers: true if the layers transferred to the next round are to be frozen (made not trainable)
  • incremental_index: the location where the new layers are to be inserted
  • incremental_layers: a serialized yaml of the layers to be added at each round

These are standard Keras models, serialised to yaml. Effectively, this is the verbatim output of a model's to_yaml().