请问LSTM预测结果为一条直线该怎么调整?

问题遇到的现象和发生背景
import random
import time

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
from keras.models import Sequential
from sklearn.metrics import r2_score  # R2
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import MinMaxScaler
from tensorflow.python.keras.models import Sequential

batch_size = 128

steps = 20

epochs = 2
def process_data():
    dataset = pd.read_csv("D:/python/conda/gegu/600028-1.csv", engine='python', index_col=['date'],parse_dates=['date'])
    columns = ['high','low','open','pre-close','amount','range','rate','volume','business','close']

    for col in columns:
        scaler = MinMaxScaler()
        dataset[col] = scaler.fit_transform(dataset[col].values.reshape(-1, 1))
    X = dataset.drop(columns=['high'],axis=1)
    y = dataset['close']
    X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.24, shuffle=False, random_state=666)

    return X_train, y_train, X_test, y_test



def create_dataset(X, y, seq_len=20):
    features = []
    targets = []  # 标签

    for i in range(0, len(X) - seq_len, 1):  # 此处的1表示步长,每隔一步滑一下
        data = X.iloc[i:i + seq_len]  # 序列数据;前闭后开
        label = y.iloc[i + seq_len]  # 标签数据
        # 保存到features和labels
        features.append(data)
        targets.append(label)

    return np.array(features), np.array(targets)


X_train, y_train, X_test, y_test = process_data()
train_dataset, train_labels = create_dataset(X_train, y_train, seq_len=20)
X_test, y_test = create_dataset(X_test, y_test, seq_len=20)

from tensorflow.keras import Sequential, layers
from keras.layers.core import Dense, Activation, Dropout
from keras.models import Sequential
from keras.layers import Bidirectional,LSTM

def build_model(neurons, dropout):
 

    model=Sequential()
    model.add(LSTM(units=neurons, input_shape=train_dataset.shape[-2:], return_sequences=True, activation='tanh'))
    model.add(Dropout(dropout))
    model.add(LSTM(units=128, return_sequences=True))
    #model.add(Dense(128 * 2, activation='sigmoid', name='attention_vec'))
    model.add(Dropout(dropout))
    model.add(LSTM(units=64))
    #model.add(LSTM(units=32,return_sequences=True))

    model.add(Dense(1,activation='sigmoid'))
    return model


def training(X):
    neurons = int(X[0])
    dropout = round(X[1], 6)
    batch_size = int(X[2])
    model = build_model(neurons, dropout)
    model.compile(optimizer='adam',
                  loss='mse')
    model.fit(
        train_dataset,
        train_labels,
        batch_size=batch_size,
        epochs=1,
        validation_data=(X_test, y_test),
        verbose=1)
    model.save(
        'neurons' + str(int(X[0])) + '_dropout' + str(dropout) + '_batch_size' + str(batch_size) + '.h5')
    # 训练完成后可直接加载模型
    # model_lstm = load_model('LSTM_bus_' + str(X[0]) + '_' + str(X[1]) + '_' + str(X[2]) + '_' + '.h5')
    pred = model.predict(X_test)
    le = len(pred)
    y_t = y_test.reshape(-1, 1)
    return pred, le, y_t


def function(ps, test, le):
    ss = sum(((abs(test - ps)) / test) / le)
    return ss


# (1) PSO Parameters
MAX_EPISODES = 2
MAX_EP_STEPS = 2
c1 = 1
c2 = 1
w = 0.5
pN = 1  # 粒子数量

# (2) LSTM Parameters
dim = 3  # 搜索维度
X = np.zeros((pN, dim))  # 所有粒子的位置和速度
V = np.zeros((pN, dim))
pbest = np.zeros((pN, dim))  # 个体经历的最佳位置和全局最佳位置
gbest = np.zeros(dim)
p_fit = np.zeros(pN)  # 每个个体的历史最佳适应值
print(p_fit.shape)
print(p_fit.shape)
t1 = time.time()

'''
神经网络第一层神经元个数: 256-259
dropout比率: 0.03-0.19
batch_size: 64-128
'''
UP = [259, 0.19, 128]
DOWN = [256, 0.03, 64]

# (4) 开始搜索
for i_episode in range(MAX_EPISODES):
    """初始化s"""
    random.seed(8)
    fit = -1e5  # 全局最佳适应值
    # 初始粒子适应度计算
    print("计算初始全局最优")
    for i in range(pN):
        for j in range(dim):
            V[i][j] = random.uniform(0, 1)
            if j == 1:
                X[i][j] = random.uniform(DOWN[j], UP[j])
            else:
                X[i][j] = round(random.randint(DOWN[j], UP[j]), 0)
        pbest[i] = X[i]
        le, pred, y_t = training(X[i])
        NN = 1
        tmp = function(pred, y_t, le)
        p_fit[i] = tmp
        if tmp > fit:
            fit = tmp
            gbest = X[i]
    print("初始全局最优参数:{:}".format(gbest))

    fitness = []  # 适应度函数
    for j in range(MAX_EP_STEPS):
        fit2 = []
        plt.title("第{}次迭代".format(i_episode))
        for i in range(pN):
            le, pred, y_t = training(X[i])
            temp = function(pred, y_t, le)
            fit2.append(temp / 1000)
            if temp > p_fit[i]:  # 更新个体最优
                p_fit[i] = temp
                pbest[i] = X[i]
                if p_fit[i] > fit:  # 更新全局最优
                    gbest = X[i]
                    fit = p_fit[i]
        print("搜索步数:{:}".format(j))
        print("个体最优参数:{:}".format(pbest))
        print("全局最优参数:{:}".format(gbest))
        # [30.          0.14277071 95.        ]
        for i in range(pN):
            V[i] = w * V[i] + c1 * random.uniform(0, 1) * (pbest[i] - X[i]) + c2 * random.uniform(0, 1) * (gbest - X[i])
            ww = 1
            for k in range(dim):
                if DOWN[k] < X[i][k] + V[i][k] < UP[k]:
                    continue
                else:
                    ww = 0
            X[i] = X[i] + V[i] * ww
        fitness.append(fit)

print('Running time: ', time.time() - t1)

# 训练模型  使用PSO找到的最好的神经元个数
neurons = int(gbest[0])
dropout = gbest[1]
batch_size = int(gbest[2])
model = build_model(neurons, dropout)
model.compile(optimizer='adam',
              loss='mse')
model.summary()
history = model.fit(train_dataset, train_labels, epochs=epochs, batch_size=batch_size, verbose=2)

# 模型预测数据
test_preds = model.predict(X_test)
test_preds = test_preds[:, 0] # 获取数组中的第1列值


# 计算r2值
score = r2_score(y_test, test_preds)
print("r^2 值为: ", score)

# 绘制 预测与真值结果
plt.figure(figsize=(16,8))
plt.plot(y_test[:1149], label="True value")
plt.plot(test_preds[:1149], label="Pred value")#预测值
plt.legend(loc='best')
plt.show()
# 显示训练结果

plt.figure(figsize=(16,8))
plt.plot(history.history['loss'], label='train loss')
plt.legend(loc='best')
plt.show()

from sklearn import metrics
print('测试集上的MSE/RMSE/MAE')
#MSE
print(metrics.mean_squared_error(y_test,test_preds))
#RMSE
print(np.sqrt(metrics.mean_squared_error(y_test,test_preds)))
#MAE
print(metrics.mean_absolute_error(y_test,test_preds))



问题相关代码,请勿粘贴截图
运行结果及报错内容
我的解答思路和尝试过的方法
我想要达到的结果

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