numpy库深拷贝（copy函数）与浅拷贝（view函数）

用等于号进行的复制不会复制真正的数据，而是让等号两边的对象指向同一块内存区域

#Simple assignments make no copy of array objects or of their data.
a = np.arange(12)
b = a
# a and b are two names for the same ndarray object
b is a
b.shape = 3,4
print(a.shape) #也是3，4  b改a也改，因为a=b
print(id(a))#2222139585808
print(id(b))#2222139585808

使用了view函数后，浅拷贝如下：

#The view method creates a new array object that looks at the same data.
c = a.view()
c is a
c.shape = 2,6
print('a=',a)
print('c=',c)
print(c[0,4])
#print a.shape
c[0,4] = 1234
#注意，深层的地方一旦改变，a和c都会发生改变
print('a=',a)
print('c=',c)

'''
a= [[   0    1    2    3]
 [1234    5    6    7]
 [   8    9   10   11]]
c= [[   0    1    2    3 1234    5]
 [   6    7    8    9   10   11]]
1234
#把C[0,4]这个元素改动后，a和c均发生了变化
a= [[   0    1    2    3]
 [1234    5    6    7]
 [   8    9   10   11]]
c= [[   0    1    2    3 1234    5]
 [   6    7    8    9   10   11]]
'''

copy可以深复制，想要完全复制一个array变量，就需要使用copy函数。

#The copy method makes a complete copy of the array and its data.
d = a.copy() 
d is a
d[0,0] = 9999
print(d)#d和a没啥联系了
print(a)#
'''
[[9999    1    2    3]
 [1234    5    6    7]
 [   8    9   10   11]]
[[   0    1    2    3]
 [1234    5    6    7]
 [   8    9   10   11]]
'''