regularizers.py

import numpy as np
from keras.datasets import mnist
from keras.layers import Activation
from keras.layers import Dense
from keras.models import Sequential
from keras.utils import np_utils

np.random.seed(1337)

nb_classes = 10
batch_size = 128
nb_epoch = 5
weighted_class = 9
standard_weight = 1
high_weight = 5
max_train_samples = 5000
max_test_samples = 1000


def get_data():
    # the data, shuffled and split between tran and test sets
    (X_train, y_train), (X_test, y_test) = mnist.load_data()
    X_train = X_train.reshape(60000, 784)[:max_train_samples]
    X_test = X_test.reshape(10000, 784)[:max_test_samples]
    X_train = X_train.astype('float32') / 255
    X_test = X_test.astype('float32') / 255

    # convert class vectors to binary class matrices
    y_train = y_train[:max_train_samples]
    y_test = y_test[:max_test_samples]
    Y_train = np_utils.to_categorical(y_train, nb_classes)
    Y_test = np_utils.to_categorical(y_test, nb_classes)
    test_ids = np.where(y_test == np.array(weighted_class))[0]

    return (X_train, Y_train), (X_test, Y_test), test_ids


def validate_regularizer(weight_reg=None, activity_reg=None):
    model = Sequential()
    model.add(Dense(50, input_shape=(784,)))
    model.add(Activation('relu'))
    model.add(Dense(10, W_regularizer=weight_reg,
                    activity_regularizer=activity_reg))
    model.add(Activation('softmax'))
    return model