计算 Python 中 Keras 神经网络的准确性

Question

我创建了一个Keras神经网络。神经网络在八个时期进行了训练，它输出了以下损失值和精度：

Epoch 1/8
2009/2009 [==============================] - 0s 177us/step - loss: 0.0824 - acc: 4.9776e-04
Epoch 2/8
2009/2009 [==============================] - 0s 34us/step - loss: 0.0080 - acc: 4.9776e-04
Epoch 3/8
2009/2009 [==============================] - 0s 37us/step - loss: 0.0071 - acc: 4.9776e-04
Epoch 4/8
2009/2009 [==============================] - 0s 38us/step - loss: 0.0071 - acc: 4.9776e-04
Epoch 5/8
2009/2009 [==============================] - 0s 35us/step - loss: 0.0070 - acc: 4.9776e-04
Epoch 6/8
2009/2009 [==============================] - 0s 38us/step - loss: 0.0071 - acc: 4.9776e-04
Epoch 7/8
2009/2009 [==============================] - 0s 36us/step - loss: 0.0068 - acc: 4.9776e-04
Epoch 8/8
2009/2009 [==============================] - 0s 40us/step - loss: 0.0070 - acc: 4.9776e-04

有没有办法找到数据集中每天的实际价格和预测之间的差异百分比？

这是神经网络：

import tensorflow as tf
import keras
import numpy as np
#import quandle
from sklearn.model_selection import train_test_split
import matplotlib.pyplot as plt
import pandas as pd
import sklearn
import math
import pandas_datareader as web
def func_stock_prediction(stockdata, start, end):
start = start
end = end
df = web.DataReader(stockdata, "yahoo", start, end)
df = df[['Close']]

previous = 5

def create_dataset(df, previous):
dataX, dataY = [], []
for i in range(len(df)-previous-1):
a = df[i:(i+previous), 0]
dataX.append(a)
dataY.append(df[i + previous, 0])
return np.array(dataX), np.array(dataY)
scaler = sklearn.preprocessing.MinMaxScaler(feature_range = (0, 1))
df = scaler.fit_transform(df)

train_size = math.ceil(len(df) * 0.5)
train, val = df[0:train_size,:], df[train_size:len(df),:]
X_train, Y_train = create_dataset(train, previous)

print(X_train)
print(Y_train)
print(X_train.shape)
print(Y_train.shape)
X_val, Y_val = create_dataset(val, previous)
X_train = np.reshape(X_train, (X_train.shape[0], 1, X_train.shape[1]))
X_val = np.reshape(X_val, (X_val.shape[0], 1, X_val.shape[1]))
model = keras.models.Sequential() 
model.add(keras.layers.Dense(units = 64, activation = 'relu', input_shape = (1, 5)))
model.add(keras.layers.Flatten())
model.add(keras.layers.Dense(units = 1, activation = 'linear'))
model.compile(loss='mean_absolute_error', 
optimizer='adam', 
metrics=['accuracy'])
history = model.fit(X_train, Y_train, epochs=8)
train = model.predict(X_train)
val = model.predict(X_val)
train = scaler.inverse_transform(train)
Y_train = scaler.inverse_transform([Y_train])
val = scaler.inverse_transform(val)
Y_val = scaler.inverse_transform([Y_val])
predictions = val

trainPlot = np.empty_like(df)
trainPlot[:, :] = np.nan
trainPlot[previous:len(train)+previous, :] = train
valPlot = np.empty_like(df)
valPlot[:, :] = np.nan
valPlot[len(train)+(previous*2)+1:len(df)-1, :] = val
inversetransform, =plt.plot(scaler.inverse_transform(df))
train, =plt.plot(trainPlot)
val, =plt.plot(valPlot)
plt.xlabel('Number of Days')
plt.ylabel('Stock Price')
plt.title("Predicted vs. Actual Stock Price Per Day")
plt.show()
func_stock_prediction("PLAY", 2010-1-1, 2020-1-1)

感谢您对此事的协助。

Answer 1

我的理解是，你想在"训练"神经网络时打印出预测中百分比的变化。如果是这样，请执行如下操作：

我用来计算与真实值偏差的百分比的逻辑是：

percent_deviance = 100 * |true - predicted| / predicted

import keras.backend as K
import numpy as np
def variation_percentage(y_pred,y_true):
deviation = np.subtract(y_pred - y_true)
scaled_deviance = np.divide(deviation,y_true) # element-wise divide
percent_deviance = np.absolute(scaled_deviance) * 100
return K.mean(percent_deviance) # returns mean percent of deviance from original value

然后在您的model.compile将其更改为：

model.compile(loss='mean_absolute_error', 
optimizer='adam', 
metrics=['accuracy', variation_percentage])

无论如何，我希望你明白逻辑。