使用多类分类，精度不会在所有时期内发生变化

Question

我正在尝试训练一个模型来解决多类分类问题。 我有一个问题是训练准确性和验证准确性不会在所有时期内发生变化。喜欢这个：

Train on 4642 samples, validate on 516 samples
Epoch 1/100
- 1s - loss: 1.7986 - acc: 0.4649 - val_loss: 1.7664 - val_acc: 0.4942
Epoch 2/100
- 1s - loss: 1.6998 - acc: 0.5017 - val_loss: 1.7035 - val_acc: 0.4942
Epoch 3/100
- 1s - loss: 1.6956 - acc: 0.5022 - val_loss: 1.7000 - val_acc: 0.4942
Epoch 4/100
- 1s - loss: 1.6900 - acc: 0.5022 - val_loss: 1.6954 - val_acc: 0.4942
Epoch 5/100
- 1s - loss: 1.6931 - acc: 0.5017 - val_loss: 1.7058 - val_acc: 0.4942
...
Epoch 98/100
- 1s - loss: 1.6842 - acc: 0.5022 - val_loss: 1.6995 - val_acc: 0.4942
Epoch 99/100
- 1s - loss: 1.6844 - acc: 0.5022 - val_loss: 1.6977 - val_acc: 0.4942
Epoch 100/100
- 1s - loss: 1.6838 - acc: 0.5022 - val_loss: 1.6934 - val_acc: 0.4942

我用 keras 的代码：

y_train = to_categorical(y_train, num_classes=11)
X_train, X_test, Y_train, Y_test = train_test_split(x_train, y_train, 
test_size=0.1, random_state=42)
model = Sequential()
model.add(Dense(64, init='normal', activation='relu', input_dim=160))
model.add(Dropout(0.3))
model.add(Dense(32, init='normal', activation='relu'))
model.add(BatchNormalization())
model.add(Dense(11, init='normal', activation='softmax'))
model.summary()
print("[INFO] compiling model...")
model.compile(optimizer=keras.optimizers.Adam(lr=0.01, beta_1=0.9, 
beta_2=0.999, epsilon=None, decay=0.0, amsgrad=False),
loss='categorical_crossentropy',
metrics=['accuracy'])
print("[INFO] training network...")
model.fit(X_train, Y_train, epochs=100, batch_size=32, verbose=2, validation_data = (X_test, Y_test))

请帮助我。谢谢！

Answer 1

我曾经遇到过类似的问题。对我来说，事实证明，确保我在x_train中没有太多缺失值(必须填充代表未知的值或填充中值(，删除真正没有帮助的列(所有列都具有相同的值(，并规范化x_train数据有帮助。

来自我的数据/模型的示例，

# load data
x_main = pd.read_csv("glioma DB X.csv")
y_main = pd.read_csv("glioma DB Y.csv")
# fill with median (will have to improve later, not done yet)
fill_median =['Surgery_SBRT','df','Dose','Ki67','KPS','BMI','tumor_size']
x_main[fill_median] = x_main[fill_median].fillna(x_main[fill_median].median())
x_main['Neurofc'] = x_main['Neurofc'].fillna(2)
x_main['comorbid'] = x_main['comorbid'].fillna(int(x_main['comorbid'].median()))
# drop surgery
x_main = x_main.drop(['Surgery'], axis=1)
# normalize all x
x_main_normalized = x_main.apply(lambda x: (x-np.mean(x))/(np.std(x)+1e-10))