我用Python中的TensorFlow 2做了我自己的第一个神经网络,我的想法是建立一个神经网络,它能够找到将二进制数(8位)翻译成十进制数的解决方案,经过几次尝试。是的,它的工作非常精确!但我不明白的是:
但我不明白的是。准确率很低
第二件事是。这个模型要训练超过200. 000个值!对于256个可能的答案。我的codemodel的故障在哪里?
#dataset
def dataset(length, num):
global testdata, solution
testdata = np.random.randint(2, size=(num, length))
solution = testdata.copy()
solution = np.zeros((num, 1))
for i in range(num):
for n in range(length):
x = testdata [i,length - n -1] * (2 ** n)
solution [i] += x
length = 8
num = 220000
dataset (length, num)
#Modell
model = tf.keras.models.Sequential([
tf.keras.layers.Dense(8, activation='relu'),
tf.keras.layers.Dense(1, activation='relu')
])
model.compile(optimizer='adam',
loss='mean_squared_error',
metrics=['accuracy'])
#Training und Evaluate
model.fit(testdata, solution, epochs=4)
model.evaluate(t_testdata, t_solution, verbose=2)
model.summary()
损失。6.6441e-05 -准确率:0.0077
是不是应该像0.77或者更高?
你不应该考虑精度作为回归问题的指标,因为你是想输出一个单一的值,即使精度的微小变化也会导致零,你可以考虑下面的例子。
考虑到你正试图预测值15,而模型返回值14.99,结果精度仍然为零。
m = tf.keras.metrics.Accuracy()
_ = m.update_state([[15]], [[14.99]])
m.result().numpy()
结果是这样的。
0.0
你可以考虑下面的回归指标列表。
我已经用上面列出的一个指标尝试了同样的问题,下面是结果。
def bin2int(bin_list):
#bin_list = [0, 0, 0, 1]
int_val = ""
for k in bin_list:
int_val += str(int(k))
#int_val = 11011011
return int(int_val, 2)
def dataset(num):
# num - no of samples
bin_len = 8
X = np.zeros((num, bin_len))
Y = np.zeros((num))
for i in range(num):
X[i] = np.around(np.random.rand(bin_len)).astype(int)
Y[i] = bin2int(X[i])
return X, Y
no_of_smaples = 220000
trainX, trainY = dataset(no_of_smaples)
testX, testY = dataset(5)
model = tf.keras.models.Sequential([
tf.keras.layers.Dense(8, activation='relu'),
tf.keras.layers.Dense(1, activation='relu')
])
model.compile(optimizer='adam',
loss='mean_absolute_error',
metrics=['mse'])
model.fit(trainX, trainY,validation_data = (testX,testY),epochs=4)
model.summary()
输出。
Epoch 1/4
6875/6875 [==============================] - 15s 2ms/step - loss: 27.6938 - mse: 2819.9429 - val_loss: 0.0066 - val_mse: 5.2560e-05
Epoch 2/4
6875/6875 [==============================] - 15s 2ms/step - loss: 0.0580 - mse: 0.1919 - val_loss: 0.0066 - val_mse: 6.0013e-05
Epoch 3/4
6875/6875 [==============================] - 16s 2ms/step - loss: 0.0376 - mse: 0.0868 - val_loss: 0.0106 - val_mse: 1.2932e-04
Epoch 4/4
6875/6875 [==============================] - 15s 2ms/step - loss: 0.0317 - mse: 0.0466 - val_loss: 0.0177 - val_mse: 3.2429e-04
Model: "sequential_11"
_________________________________________________________________
Layer (type) Output Shape Param #
=================================================================
dense_24 (Dense) multiple 72
_________________________________________________________________
dense_25 (Dense) multiple 9
_________________________________________________________________
round_4 (Round) multiple 0
=================================================================
Total params: 81
Trainable params: 81
Non-trainable params: 0
Predict:
model.predict([[0., 0., 0., 0., 0., 1., 1., 0.]])
array([[5.993815]], dtype=float32)