我使用的是用 Keras 库实现的神经网络,下面是训练期间的结果。最后,它会打印出测试分数和测试准确度。我无法确切地弄清楚分数代表什么,但我假设的准确性是运行测试时正确的预测数量。
Epoch 1/15 1200/1200 [==============================] - 4s - loss: 0.6815 - acc: 0.5550 - val_loss: 0.6120 - val_acc: 0.7525
Epoch 2/15 1200/1200 [==============================] - 3s - loss: 0.5481 - acc: 0.7250 - val_loss: 0.4645 - val_acc: 0.8025
Epoch 3/15 1200/1200 [==============================] - 3s - loss: 0.5078 - acc: 0.7558 - val_loss: 0.4354 - val_acc: 0.7975
Epoch 4/15 1200/1200 [==============================] - 3s - loss: 0.4603 - acc: 0.7875 - val_loss: 0.3978 - val_acc: 0.8350
Epoch 5/15 1200/1200 [==============================] - 3s - loss: 0.4367 - acc: 0.7992 - val_loss: 0.3809 - val_acc: 0.8300
Epoch 6/15 1200/1200 [==============================] - 3s - loss: 0.4276 - acc: 0.8017 - val_loss: 0.3884 - val_acc: 0.8350
Epoch 7/15 1200/1200 [==============================] - 3s - loss: 0.3975 - acc: 0.8167 - val_loss: 0.3666 - val_acc: 0.8400
Epoch 8/15 1200/1200 [==============================] - 3s - loss: 0.3916 - acc: 0.8183 - val_loss: 0.3753 - val_acc: 0.8450
Epoch 9/15 1200/1200 [==============================] - 3s - loss: 0.3814 - acc: 0.8233 - val_loss: 0.3505 - val_acc: 0.8475
Epoch 10/15 1200/1200 [==============================] - 3s - loss: 0.3842 - acc: 0.8342 - val_loss: 0.3672 - val_acc: 0.8450
Epoch 11/15 1200/1200 [==============================] - 3s - loss: 0.3674 - acc: 0.8375 - val_loss: 0.3383 - val_acc: 0.8525
Epoch 12/15 1200/1200 [==============================] - 3s - loss: 0.3624 - acc: 0.8367 - val_loss: 0.3423 - val_acc: 0.8650
Epoch 13/15 1200/1200 [==============================] - 3s - loss: 0.3497 - acc: 0.8475 - val_loss: 0.3069 - val_acc: 0.8825
Epoch 14/15 1200/1200 [==============================] - 3s - loss: 0.3406 - acc: 0.8500 - val_loss: 0.2993 - val_acc: 0.8775
Epoch 15/15 1200/1200 [==============================] - 3s - loss: 0.3252 - acc: 0.8600 - val_loss: 0.2960 - val_acc: 0.8775
400/400 [==============================] - 0s
Test score: 0.299598811865
Test accuracy: 0.88
看着Keras documentation ,我还是不明白分数是什么。对于评估功能,它说:
Returns the loss value & metrics values for the model in test mode.
我注意到的一件事是,当测试准确度较低时,分数较高,而当准确度较高时,分数较低。
最佳答案
作为引用,代码的两个相关部分:
model.compile(loss='binary_crossentropy',
optimizer='adam',
metrics=['accuracy'])
score, acc = model.evaluate(x_test, y_test,
batch_size=batch_size)
print('Test score:', score)
print('Test accuracy:', acc)
分数是对给定输入的损失函数的评估。
训练网络是寻找最小化损失函数(或成本函数)的参数。
这里的成本函数是
binary_crossentropy
.对于目标 T 和网络输出 O,二元交叉熵可以定义为
f(T,O) = -(T*log(O) + (1-T)*log(1-O) )
所以你看到的分数就是对它的评价。
如果你给它输入一批输入,它很可能会返回平均损失。
所以是的,如果您的模型具有较低的损失(在测试时),它通常应该具有较低的预测误差。
关于neural-network - 使用 Keras 评估模型时的测试分数与测试准确性,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43589842/