我们调用第三方的神经网络python组件继续进行更复杂的函数拟合,这次拟合一个比sin函数更复杂的函数f(x)=sin(x)*0.5+cos(x)*0.5
python代码如下
#!/usr/bin/env python #-*- coding: utf-8 -*- #bp ann 函数拟合sin*0.5+cos*0.5 import neurolab as nl import numpy as np import matplotlib.pyplot as plt isdebug=False #x和d样本初始化 train_x =[] d=[] samplescount=1000 myrndsmp=np.random.rand(samplescount) for yb_i in xrange(0,samplescount): train_x.append([myrndsmp[yb_i]*4*np.pi-2*np.pi]) for yb_i in xrange(0,samplescount): d.append(np.sin(train_x[yb_i])*0.5+np.cos(train_x[yb_i])*0.5) myinput=np.array(train_x) mytarget=np.array(d) bpnet = nl.net.newff([[-2*np.pi, 2*np.pi]], [5, 1]) err = bpnet.train(myinput, mytarget, epochs=800, show=100, goal=0.02) simd=[] for xn in xrange(0,len(train_x)): # print "=====================" # print u"样本:%f=> "%(train_x[xn][0]) simd.append(bpnet.sim([train_x[xn]])[0][0]) # print simd[xn] # print u"--正确目标值--" # print d[xn] # print "=====================" temp_x=[] temp_y=simd temp_d=[] i=0 for mysamp in train_x: temp_x.append(mysamp[0]) temp_d.append(d[i][0]) i+=1 x_max=max(temp_x) x_min=min(temp_x) y_max=max(max(temp_y),max(d))+0.2 y_min=min(min(temp_y),min(d))-0.2 plt.xlabel(u"x") plt.xlim(x_min, x_max) plt.ylabel(u"y") plt.ylim(y_min, y_max) plt.title("http://blog.csdn.net/myhaspl" ) lp_x1 = temp_x lp_x2 = temp_y lp_d = temp_d plt.plot(lp_x1, lp_x2, 'r*') plt.plot(lp_x1,lp_d,'b*') plt.show()
>>> runfile(r'I:ook_progann_bpnhsincos1.py', wdir=r'I:ook_prog')
Epoch: 100; Error: 0.528978849953;
Epoch: 200; Error: 0.33336612138;
Epoch: 300; Error: 0.253337487331;
Epoch: 400; Error: 0.20472927421;
Epoch: 500; Error: 0.202153963051;
Epoch: 600; Error: 0.19900731385;
Epoch: 700; Error: 0.197426245762;
Epoch: 800; Error: 0.193607559472;
The maximum number of train epochs is reached
>>>
拟合效果为: