我制作了7个班级的CNN分类器。我正在训练一个顺序模型，这里
model = Sequential()
model.add(Conv2D(C1, (3, 3), activation='relu', input_shape=input_shape))
model.add(Conv2D(3*C1, (3, 3), activation='relu'))
model.add(Dropout(0.25))
model.add(Flatten())
model.add(Dense(6*numPCAcomponents, activation='relu'))
model.add(Dropout(0.5))
model.add(Dense(7, activation='softmax'))
然后我正在编译模型：
sgd = SGD(lr=0.0001, decay=1e-6, momentum=0.9, nesterov=True)
model.compile(loss='categorical_crossentropy', optimizer=sgd, metrics=['accuracy'])
然后使用此模型评估测试集。问题出在这里。当我启动mode.evaluate函数时出现此错误：
Error when checking target: expected dense_2 to have shape (7,) but got array with shape (4,)
我评估的方式就在这里，
Y_pred = model.predict(X_test)
y_pred = np.argmax(Y_pred, axis=1)
target_names = ['A','B','C','D','E','F','G']
classification = classification_report(np.argmax(y_test, axis=1), y_pred, target_names=target_names)
confusion = confusion_matrix(np.argmax(y_test, axis=1), y_pred)
score = model.evaluate(X_test, y_test, batch_size=32)
Test_Loss = score[0]*100
Test_accuracy = score[1]*100
为什么会出现这个错误？如何解决这个错误？我多次检查了一切，但找不到错误。