斯坦福coursera作业题神经网络训练数字识别 Visualizing the data python实现

from PIL import Image
import numpy as np
import matplotlib.pyplot as plt
import scipy.io as sio
import math
import random
def displayData(x,y,start,number):            #start为起始行，number为输出图像的行数和列数
m = int(np.sqrt(len(x[0])))
data = np.zeros((number*m, number*m))
for l in range(start,start+number):
for k in range(start,start+number):
h=0
for i in range((l-start)*m,(l+1-start)*m):
for j in range((k-start)*m,(k+1-start)*m):
data[j][i] = x[l*m+k][h]
h = h + 1
data = data * 255
new_im = Image.fromarray(data.astype(np.uint8))
plt.imshow(data, cmap=plt.cm.gray, interpolation='nearest')
new_im.show()
return None
data = sio.loadmat('ex4data1.mat')       #x为5000*400，y为5000*1，theta1为25*401，theta2为10*26
y = data['y']
x = data['X']
displayData(x, y,0,30)