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from keras.models import Sequential |
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from keras.layers import Dense, Activation, Convolution1D, Flatten, MaxPooling1D, Lambda, Convolution2D, Flatten, Reshape, LSTM, Dropout, TimeDistributed, Permute |
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from keras.regularizers import l2 |
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from keras.optimizers import Adam |
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import numpy as np |
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def generate_models(x_shape, number_of_classes, number_of_models=5, model_type=None, **kwargs): |
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""" Generate one or multiple Keras models with random (default), or predefined, hyperparameters.""" |
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models = [] |
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for _ in range(0, number_of_models): |
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if model_type == None: # random model choice: |
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current_model_type = 'CNN' if np.random.random( |
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) < 0.5 else 'DeepConvLSTM' |
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else: # user-defined model choice: |
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current_model_type = model_type |
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if current_model_type == 'CNN': |
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generate_model = generate_CNN_model #object is a function |
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generate_hyperparameter_set = generate_CNN_hyperparameter_set |
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if current_model_type == 'DeepConvLSTM': |
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generate_model = generate_DeepConvLSTM_model #object is a function |
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generate_hyperparameter_set = generate_DeepConvLSTM_hyperparameter_set |
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hyperparameters = generate_hyperparameter_set(**kwargs) |
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models.append( |
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(generate_model(x_shape, number_of_classes, **hyperparameters), hyperparameters, current_model_type)) |
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return models |
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def generate_DeepConvLSTM_model(x_shape, class_number, filters, lstm_dims, learning_rate=0.01, |
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regularization_rate=0.01): |
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""" |
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Generate a model with convolution and LSTM layers. |
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See Ordonez et al., 2016, http://dx.doi.org/10.3390/s16010115 |
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The compiled Keras model is returned. |
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""" |
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dim_length = x_shape[1] # number of samples in a time series |
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dim_channels = x_shape[2] # number of channels |
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output_dim = class_number # number of classes |
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weightinit = 'lecun_uniform' # weight initialization |
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model = Sequential() # initialize model |
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# reshape a 2 dimensional array per file/person/object into a |
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# 3 dimensional array |
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model.add( |
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Reshape(target_shape=(1, dim_length, dim_channels), input_shape=(dim_length, dim_channels))) |
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for filt in filters: |
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# filt: number of filters used in a layer |
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# filters: vector of filt values |
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model.add( |
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Convolution2D(filt, nb_row=3, nb_col=1, border_mode='same', |
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W_regularizer=l2(regularization_rate),init = weightinit)) |
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model.add(Activation('relu')) |
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# reshape 3 dimensional array back into a 2 dimensional array, |
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# but now with more dept as we have the the filters for each channel |
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model.add(Reshape(target_shape=(dim_length, filters[-1] * dim_channels))) |
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for lstm_dim in lstm_dims: |
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model.add(LSTM(output_dim=lstm_dim, return_sequences=True, |
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activation='tanh')) |
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model.add(Dropout(0.5)) #dropout before the dense layer |
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# set up final dense layer such that every timestamp is given one classification |
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model.add(TimeDistributed(Dense(output_dim, W_regularizer=l2(regularization_rate)))) |
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model.add(Activation("softmax")) |
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# Final classification layer - per timestep |
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model.add(Lambda(lambda x: x[:, -1, :], output_shape=[output_dim])) |
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model.compile(loss='categorical_crossentropy', |
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optimizer=Adam(lr=learning_rate), |
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metrics=['accuracy']) |
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return model |
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def generate_CNN_model(x_shape, class_number, filters, fc_hidden_nodes, learning_rate=0.01, regularization_rate=0.01): |
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""" |
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Generate a convolutional neural network (CNN) model. |
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The compiled Keras model is returned. |
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""" |
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dim_length = x_shape[1] # number of samples in a time series |
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dim_channels = x_shape[2] # number of channels |
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outputdim = class_number # number of classes |
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weightinit = 'lecun_uniform' # weight initialization |
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model = Sequential() |
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model.add( |
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Convolution1D(filters[0], 3, border_mode='same', input_shape=(dim_length, dim_channels), |
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W_regularizer=l2(regularization_rate),init = weightinit)) |
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for filter_number in filters[1:]: |
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model.add(Convolution1D(filter_number, 3, border_mode='same', |
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W_regularizer=l2(regularization_rate),init = weightinit)) |
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model.add(Activation('relu')) |
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model.add(Flatten()) |
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model.add(Dense(output_dim=fc_hidden_nodes, |
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W_regularizer=l2(regularization_rate),init = weightinit)) # Fully connected layer |
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model.add(Activation('relu')) # Relu activation |
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model.add(Dense(output_dim=outputdim,init = weightinit)) |
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model.add(Activation("softmax")) # Final classification layer |
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model.compile(loss='categorical_crossentropy', |
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optimizer=Adam(lr=learning_rate), |
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metrics=['accuracy']) |
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return model |
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def generate_CNN_hyperparameter_set(min_layers=1, max_layers=10, |
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min_filters=10, max_filters=100, |
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min_fc_nodes=10, max_fc_nodes=100): |
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""" Generate a hyperparameter set that define a CNN model.""" |
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hyperparameters = generate_base_hyper_parameter_set() |
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number_of_layers = np.random.randint(min_layers, max_layers) |
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hyperparameters['filters'] = np.random.randint( |
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min_filters, max_filters, number_of_layers) |
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hyperparameters['fc_hidden_nodes'] = np.random.randint( |
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min_fc_nodes, max_fc_nodes) |
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return hyperparameters |
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def generate_DeepConvLSTM_hyperparameter_set( |
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min_conv_layers=1, max_conv_layers=10, |
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min_conv_filters=10, max_conv_filters=100, |
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min_lstm_layers=1, max_lstm_layers=5, |
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min_lstm_dims=10, max_lstm_dims=100): |
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""" Generate a hyperparameter set that defines a DeepConvLSTM model.""" |
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hyperparameters = generate_base_hyper_parameter_set() |
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number_of_conv_layers = np.random.randint(min_conv_layers, max_conv_layers) |
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hyperparameters['filters'] = np.random.randint( |
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min_conv_filters, max_conv_filters, number_of_conv_layers) |
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number_of_lstm_layers = np.random.randint(min_lstm_layers, max_lstm_layers) |
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hyperparameters['lstm_dims'] = np.random.randint( |
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min_lstm_dims, max_lstm_dims, number_of_lstm_layers) |
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return hyperparameters |
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def generate_base_hyper_parameter_set(): |
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""" Generate a base set of hyperparameters that are necessary for any model, but sufficient for none.""" |
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hyperparameters = {} |
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hyperparameters['learning_rate'] = get_learning_rate() |
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hyperparameters['regularization_rate'] = get_regularization() |
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return hyperparameters |
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def get_learning_rate(low=1, high=4): |
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""" Return random learning rate 10^-n where n is sampled uniformly between low and high bounds.""" |
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result = 10 ** (-np.random.uniform(low, high)) |
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return result |
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def get_regularization(low = 1, high = 4): |
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""" Return random regularization rate 10^-n where n is sampled uniformly between low and high bounds.""" |
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return 10**(-np.random.uniform(low, high)) |
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NLeSC /
mcfly
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