from numpy import *
import time
import pylab as plt
a=zeros([10,10])
b=ones([10,10])
dx=dy=0.1
x,y = mgrid[:1:dx,:1:dy]
def add(a,b):
a[1:-1,1:-1]=a[1:-1,1:-1]+b[1:-1,1:-1]
data=0
print(data)
for i in range(4):
#data.append(a)
print (a)
add(a,b)
上面的是澄清我遇到的问题的说明代码。代码输出的内容是:
[[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]]
[[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 1. 1. 1. 1. 1. 1. 1. 1. 0.]
[ 0. 1. 1. 1. 1. 1. 1. 1. 1. 0.]
[ 0. 1. 1. 1. 1. 1. 1. 1. 1. 0.]
[ 0. 1. 1. 1. 1. 1. 1. 1. 1. 0.]
[ 0. 1. 1. 1. 1. 1. 1. 1. 1. 0.]
[ 0. 1. 1. 1. 1. 1. 1. 1. 1. 0.]
[ 0. 1. 1. 1. 1. 1. 1. 1. 1. 0.]
[ 0. 1. 1. 1. 1. 1. 1. 1. 1. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]]
[[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 2. 2. 2. 2. 2. 2. 2. 2. 0.]
[ 0. 2. 2. 2. 2. 2. 2. 2. 2. 0.]
[ 0. 2. 2. 2. 2. 2. 2. 2. 2. 0.]
[ 0. 2. 2. 2. 2. 2. 2. 2. 2. 0.]
[ 0. 2. 2. 2. 2. 2. 2. 2. 2. 0.]
[ 0. 2. 2. 2. 2. 2. 2. 2. 2. 0.]
[ 0. 2. 2. 2. 2. 2. 2. 2. 2. 0.]
[ 0. 2. 2. 2. 2. 2. 2. 2. 2. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]]
[[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 3. 3. 3. 3. 3. 3. 3. 3. 0.]
[ 0. 3. 3. 3. 3. 3. 3. 3. 3. 0.]
[ 0. 3. 3. 3. 3. 3. 3. 3. 3. 0.]
[ 0. 3. 3. 3. 3. 3. 3. 3. 3. 0.]
[ 0. 3. 3. 3. 3. 3. 3. 3. 3. 0.]
[ 0. 3. 3. 3. 3. 3. 3. 3. 3. 0.]
[ 0. 3. 3. 3. 3. 3. 3. 3. 3. 0.]
[ 0. 3. 3. 3. 3. 3. 3. 3. 3. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]]
但是代码输出:
[[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]]
[[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]]
[[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]]
[[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 4. 4. 4. 4. 4. 4. 4. 4. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]]
那么这种问题有解决办法吗?
谢谢~
有人提出了以下解决方案:
from numpy import*
import time
import pylab as plt
dx=dy=0.1
x,y = mgrid[:1:dx,:1:dy]
data=[]
for i in range(4):
a=zeros([10,10])
b=ones([10,10])
a[1:-1,1:-1] = b[1:-1,1:-1]*i
data.append(a)
for k in range(4):
print(data[k])
然而，这并不是解决这类问题的典型方法。这是因为如果我使用的[add]函数或示例中的a, b数组发生变化，则此解决方案将失去其效果
换句话说，该代码给出了所需的输出:
for _ in range(4):
print(a)
add(a, b)
但这不是:
data = []
for _ in range(4):
data.append(a)
add(a, b)
for d in data:
print(d)
让我们先看一个简单的例子，它将帮助你理解发生了什么:
In [184]: a = zeros(3)
In [185]: a
Out[185]: array([ 0., 0., 0.])
In [186]: b = a
In [187]: b[0] = 99
In [188]: print(a)
[ 99. 0. 0.]
你知道发生了什么吗?我们使一个数组b与数组a相同，然后修改数组b也改变了数组a !
之所以会发生，是因为实际上只有一个数组对象!"变量"a和b只是同一个底层对象的两个名称。因此，我们可以通过使用名称b来修改数组，如果我们使用名称a，我们也会看到变化，因为它是相同的数组。
如果将a附加到列表中，也会发生相同的情况。该列表包含对对象的引用。但是在您的例子中，所有引用都指向同一个对象!
data = []
for _ in range(4):
data.append(a.copy())
add(a, b)