pytorch:RNN_regression

#!/usr/bin/env python
# -*- coding: UTF-8 -*-
'''=================================================
@Project -> File   ：pytorch學習 -> RNN_regression
@IDE    ：PyCharm
@Author ：zgq
@Date   ：2021/3/23 12:11
@Desc   ：
=================================================='''
import torch
from torch import nn
from torch.autograd import Variable
import numpy as np
import matplotlib.pyplot as plt

torch.manual_seed(1)

#hyper parameters
TIME_STEP=10
INPUT_SIZE=1
LR=0.02

#show data
steps=np.linspace(0,np.pi*2,100,dtype=np.float32)
x_np=np.sin(steps)
y_np=np.cos(steps)
plt.plot(steps, y_np, 'r-', label='target (cos)')
plt.plot(steps, x_np, 'b-', label='input (sin)')
plt.legend(loc='best')
plt.show()

class RNN(nn.Module):
    def __init__(self):
        super(RNN, self).__init__()
        self.rnn=nn.RNN(        #上一節使用的是LSTM，這次使用普通的rnn
            input_size=INPUT_SIZE,
            hidden_size=32,
            num_layers=1,
            batch_first=True
        )
        self.out=nn.Linear(32,1)

    def forward(self,x,h_state):
        r_out,h_state=self.rnn(x,h_state)
        #他們分别的shape：
        #x(batch,time_step,input_size
        #h_state(n_layers,batch,hidden_size)
        #r_out(batch,time_step,output_size

        outs=[]
        for time_step in range(r_out.size(1)):      #将每個time_step中的hiddenlayer資料取出來來做一個上面的nn.Liner來将他從32維變成一個回歸的1維,
            #最後要将所有步驟的輸出都放入這個outs 的list中
            outs.append(self.out(r_out[:,time_step,:]))        #self.out中的輸入就是我們這個time——steo時間點的輸入

        return torch.stack(outs,dim=1),h_state

rnn=RNN()
print(rnn)

optimizer=torch.optim.Adam(rnn.parameters(),lr=LR)
loss_func=nn.MSELoss()

h_state=None

plt.figure(1, figsize=(12, 5))
plt.ion()           # continuously plot

for step in range(100):
    start,end=step*np.pi,(step+1)*np.pi
    #use sin predict cos
    steps=np.linspace(start,end,TIME_STEP,dtype=np.float32)
    x_np=np.sin(steps)
    y_np=np.cos(steps)

    #處理資料加一個次元
    x=Variable(torch.from_numpy(x_np[np.newaxis,:,np.newaxis]))
    y=Variable(torch.from_numpy(x_np[np.newaxis,:,np.newaxis]))

    prediction,h_state=rnn(x,h_state)
    h_state=h_state.data      #!!再次傳入的時候一定要用variable再包起來

    loss=loss_func(prediction,y)
    optimizer.zero_grad()
    loss.backward()
    optimizer.step()

    # plotting
    plt.plot(steps, y_np.flatten(), 'r-')
    plt.plot(steps, prediction.data.numpy().flatten(), 'b-')
    plt.draw();
    plt.pause(0.05)

plt.ioff()
plt.show()