boston_housing.py

import numpy as np
from keras.datasets import boston_housing
from keras import models
from keras import layers

(train_data, train_targets), (test_data, test_targets) = boston_housing.load_data()

mean = train_data.mean(axis=0)
train_data -= mean
std = train_data.std(axis=0)
train_data /= std
test_data -= mean
test_data /= std
print(mean)
print(std)

def build_model():
    model = models.Sequential()
    model.add(layers.Dense(64, activation='relu',input_shape=(train_data.shape[1],)))
    model.add(layers.Dense(64, activation='relu'))
    model.add(layers.Dense(1))
    model.compile(optimizer='rmsprop', loss='mse', metrics=['mae'])
    return model

k = 4
num_val_samples = len(train_data) // k
num_epochs = 100
all_scores = []

for i in range(k):
    print('processing fold #', i)
    val_data = train_data[i * num_val_samples: (i + 1) * num_val_samples]
    val_targets = train_targets[i * num_val_samples: (i + 1) * num_val_samples]
    partial_train_data = np.concatenate([train_data[:i * num_val_samples],train_data[(i + 1) * num_val_samples:]],axis=0)
    partial_train_targets = np.concatenate([train_targets[:i * num_val_samples],train_targets[(i + 1) * num_val_samples:]],axis=0)

    model = build_model()
    model.fit(partial_train_data, partial_train_targets,epochs=num_epochs, batch_size=1, verbose=0)
    val_mse, val_mae = model.evaluate(val_data, val_targets, verbose=0)
    all_scores.append(val_mae)

print(all_scores)
print(np.mean(all_scores))