機械学習/ドロップアウト

ドロップアウトは、 過学習を防ぎモデルの精度をあげるための手法の一つ

import numpy as np
import matplotlib.pyplot as plt
from keras.datasets import mnist
from keras.layers import Activation, Dense, Dropout
from keras.models import Sequential, load_model
from keras import optimizers
from keras.utils.np_utils import to_categorical

(X_train, y_train), (X_test, y_test) = mnist.load_data()

X_train = X_train.reshape(X_train.shape[0], 784)[:6000]
X_test = X_test.reshape(X_test.shape[0], 784)[:1000]
y_train = to_categorical(y_train)[:6000]
y_test = to_categorical(y_test)[:1000]

model = Sequential()
model.add(Dense(256, input_dim=784))
model.add(Activation("sigmoid"))
model.add(Dense(128))
model.add(Activation("sigmoid"))

model.add(Dropout(rate=0.5))

model.add(Dense(10))
model.add(Activation("softmax"))

sgd = optimizers.SGD(lr=0.1)

model.compile(optimizer=sgd, loss="categorical_crossentropy", metrics=["accuracy"])

history = model.fit(X_train, y_train, batch_size=32, epochs=5, verbose=1, validation_data=(X_test, y_test))

#acc, val_accのプロット
plt.plot(history.history["acc"], label="acc", ls="-", marker="o")
plt.plot(history.history["val_acc"], label="val_acc", ls="-", marker="x")
plt.ylabel("accuracy")
plt.xlabel("epoch")
plt.legend(loc="best")
plt.show()