09 Array copy
b = np.arange(1,13).reshape((3,4))
print(a)
sub_a = a[:2,:2] #获取第一、二行，第一、二列
print(sub_a)
Modify the value of the first row and second column
sub_a[0][0] = 100 # 数组进行深拷贝对原数组也进行了修改
print(sub_a)
print(a)
sub_aa = np.copy(a[:2][:2]) # 数组进行深拷贝不对原数组影响
sub_aa[0,0] = 222
print(sub_aa)
print(a)
