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Drawing

Tune the hyperparameters of your PyTorch models with HyperSearch.

Requirements

API

Note: We currently only support FC networks. ConvNet support coming soon!

  • Install requirements using:
pip install -r requirements.txt
  • Define your model in model.py. This should return a nn.Sequential object. Take note of the last layer, i.e. using nn.LogSoftmax() vs. nn.Softmax() will require possible changes in the training method. For example, let's define a 4 layer FC network as follows:
Sequential(
  (0): Linear(in_features=784, out_features=512)
  (1): ReLU()
  (2): Linear(in_features=512, out_features=256)
  (3): ReLU()
  (4): Linear(in_features=256, out_features=128)
  (5): ReLU()
  (6): Linear(in_features=128, out_features=10)
  (7): LogSoftmax()
)
  • Write your own data_loader.py if you do not have a dataset that is supported by torchvision.datasets. Else, slightly edit data_loader.py to suit your dataset of choice: CIFAR-10, CIFAR-100, Fashion-MNIST, MNIST, etc.
  • Create your hyperparameter dictionary in main.py. You must follow the following syntax:
params = {
    '2_hidden': ['quniform', 512, 1000, 1],
    '4_hidden': ['quniform', 128, 512, 1],
    'all_act': ['choice', [[0], ['choice', ['selu', 'elu', 'tanh']]]],
    'all_dropout': ['choice', [[0], ['uniform', 0.1, 0.5]]],
    'all_batchnorm': ['choice', [0, 1]],
    'all_l2': ['uniform', 1e-8, 1e-5],
    'optim': ['choice', ["adam", "sgd"]],
}

Keys are of the form {layer_num}_{hyperparameter} where layer_num can be a layer from your nn.Sequential model or all to signify all layers. Values are of the form [distribution, x] where distribution can be one of uniform, quniform, choice, etc.

For example, 2_hidden: ['quniform', 512, 1000, 1] means to sample the hidden size of layer 2 of the model (Linear(in_features=512, out_features=256)) from a quantile uniform distribution with lower bound 512, upper bound 1000 and q = 1.

all_dropout: ['choice', [[0], ['uniform', 0.1, 0.5]]] means to choose whether to apply dropout or not to all layers. choice means pick from elements in a list and [0] means False while the other choice, implicitly implied to mean true, means to sample Dropout probability from a uniform distribution with lower bound 0.1 and upper bound 0.5.

  • Edit the config.py file to suit your needs. Concretely, you can edit the hyperparameters of HyperBand, the default learning rate, the dataset of choice, etc. There are 2 parameters that control the HyperBand algorithm:
    • max_iter: maximum number of iterations allocated to a given hyperparam config
    • eta: proportion of configs discarded in each round of successive halving.
    • epoch_scale: a boolean indicating whether max_iter should be computed in terms of mini-batch iterations or epochs. This is useful if you want to speed up HyperBand and don't want to evaluate a full pass on a large dataset.

Set max_iter to the usual amount you would train neural networks for. It's mostly a rule fo thumb, but something in the range [80, 150] epochs. Larger values of nu correspond to a more aggressive elimination schedule and thus fewer rounds of elimination. Increase to receive faster results at the cost of a sub-optimal performance. Authors advise a value of 3 or 4.

  • As a last step, depending on the last layer in your model, you may wish to edit the train_one_epoch() method in the hyperband.py file. The default uses F.nll_loss because it assumes the user used LogSoftmax but feel free to edit the loss to tailor to your needs.

Finally, you can run the algorithm using:

python main.py

Hyperparameter Support

  • Activation
    • all
    • per layer
  • L1/L2 regularization (weights & biases)
    • all
    • per layer
  • Add Batch Norm
    • sandwiched between every layer
  • Add Dropout
    • sandwiched between every layer
  • Add Layers
    • conv Layers
    • fc Layers
  • Change Layer Params
    • change fc output size
    • change conv params
  • Optimization
    • batch size
    • learning rate
    • optimizer (adam, sgd)

Todo

  • conv nn support
  • max exploration option (s = s_max)
  • input error checking
  • improve plotting and logging
  • multi-gpu and multi-cpu support

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