我有一个名为“graph_main”的BipartiteGraph类的实例，现在我需要保持此实例不变，但创建另一个名为“graph1”的相同类实例，但是因某种原因，当我根本没有使用它时，“graph_main”也会不断地发生变化。我刚学Python，只有几周的经验。如果您可以指向相关文档以了解Python中对象的作用域，我将非常感激。
MWE：
import numpy
import testBipartiteUtils
import random
#These are Bipartite graph parameters
N=30 #No of Bit Nodes
K=10 #No of Check Nodes
rdeg=2
graph_main = testBipartiteUtils.BipartGraph([])
for NodeIndex in range(0, K):
graph_main.addBitNode(NodeIndex)#Adding Bit Node. No edges added
for NodeIndex in range(0, N):
graph_main.addChkNode(NodeIndex)#Adding Check Node. No edges added
attachments=random.sample(range(0,K),rdeg)
for j in attachments:
graph_main.addEdge([j,NodeIndex])
for z in range(0,10):
chan=[]
for i in range(0,N):
chan.append(0)
graph1=graph_main **#creating a new object identical to graph_main?**
PeelGraph=testBipartiteUtils.Peeling(graph1,chan)
PeelGraph.zeroStep()
print "graph_main Nodes are-",len(graph_main.BitNodes),len(graph_main.ChkNodes)
print "graph1 Nodes are-",len(graph1.BitNodes),len(graph1.ChkNodes)
del PeelGraph
print "z=",z
我提供了我的Utils文件，以便有人想运行它并查看，但我非常怀疑这是必要的。因此，我期望每次模拟在graph_main（它是一个二分图类）中具有恒定数量的Bit和Check节点输出，因为我没有更改它。在这里，我假设graph1 = graph_main创建了一个与现有graph_main相同的新对象。这是正确的吗？我的错误在其他地方吗？
testBipartiteUtils.py
import numpy
class Edge:
def __init__(self, n1, n2):
"""Constructor. Takes bit and check node IDs as arguments"""
self.node1=n1
self.node2=n2
def getNodes(self):
"""Returns a list containing the bit and check nodes for this edge"""
return [self.node1, self.node2]
def hasNodes(self, n1, n2):
"""Takes two node IDs. Returns true if the IDs match the two nodes of this edge in that order."""
if(self.node1==n1 and self.node2==n2):
return True
return False
class BitNode:
""" Basic node class."""
def __init__(self, name):
"""Constructor. Takes a node ID"""
self.ID=name
self.neighbors=[]
self.degree= 0
def addNeighbors(self, nbs):
"""Adds a list of neighbors to the current list. Takes a list of node IDs"""
for i in range(0, len(nbs)):
if(not nbs[i] in self.neighbors):
self.neighbors.append(nbs[i])
self.degree+=1
def getID(self):
"""Returns node ID"""
return self.ID
def getNeighbors(self):
"""Returns list of neighbor IDs"""
return self.neighbors
class ChkNode:
def __init__(self, name):
"""Constructor. Takes a node ID"""
self.ID=name
self.neighbors=[]
self.chan = int(-1)
self.degree= 0
def addNeighbors(self, nbs):
"""Adds a list of neighbors to the current list. Takes a list of node IDs"""
for i in range(0, len(nbs)):
if(not nbs[i] in self.neighbors):
self.neighbors.append(nbs[i])
self.degree+=1
def getID(self):
"""Returns node ID"""
return self.ID
def getNeighbors(self):
"""Returns list of neighbor IDs"""
return self.neighbors
class BipartGraph:
def __init__(self, eds):
"""Constructor. Takes a list of edge primitives, which is a list of two node IDs.
Iterates through the edges, creates nodes for unique node IDs, and adds all edges and nodes.
"""
self.size = 0
self.BitNodes = []
self.ChkNodes = []
self.edges = []
for i in range(0, len(eds)):
self.addEdge(eds[i])
def containsEdge(self, edgep):
"""Checks for an edge in the graph. Takes an edge primitive, which is a list of two node IDs. First ID is bit node, second ID is of Check node"""
for e in self.edges:
if(e.hasNodes(edgep[0], edgep[1])):
return True
def getBitNode(self, name):
"""Checks if a given Bit Node ID exists in the graph. If not, it creates and adds a Bit Node for the given ID. Returns the Bit Node"""
for i in range(0, len(self.BitNodes)):
if(self.BitNodes[i].getID()==name):
return self.BitNodes[i]
newNode = BitNode(name)
self.BitNodes.append(newNode)
return self.BitNodes[len(self.BitNodes)-1]
def getChkNode(self, name):
"""Checks if a given Chk Node ID exists in the graph. If not, it creates and adds a Chk Node for the given ID. Returns the Chk Node"""
for i in range(0, len(self.ChkNodes)):
if(self.ChkNodes[i].getID()==name):
return self.ChkNodes[i]
newNode = ChkNode(name)
self.ChkNodes.append(newNode)
return self.ChkNodes[len(self.ChkNodes)-1]
def getEdges(self):
"""Returns list of edges"""
return self.edges
def addBitNode(self, name):
"""Adds a Bit node, based on Bit node ID"""
newNode = BitNode(name)
self.BitNodes.append(newNode)
def addChkNode(self, name):
"""Adds a Check node, based on node ID"""
newNode = ChkNode(name)
self.ChkNodes.append(newNode)
def addEdge(self, edgep):
"""Adds an edge into the graph, and updates neighbors & degrees of relevant nodes.
Takes an edge primitive, a list of two node IDs
"""
if(not self.containsEdge(edgep)):
no1 = self.getBitNode(edgep[0])
no2 = self.getChkNode(edgep[1])
newEdge = Edge(edgep[0], edgep[1])
self.edges.append(newEdge)
no1.addNeighbors([no2.getID()])
no2.addNeighbors([no1.getID()])
class Peeling:
"""peeling decoder on a Bipartite graph class.
"""
def __init__(self, G,chan):
"""Constructor. Takes a graph and channel output vector as arguments"""
self.graph=G
for i in range(0,len(self.graph.ChkNodes)):
self.graph.ChkNodes[i].chan=chan[i]
self.deg1Chks=[]
def zeroStep(self):
self.graph.BitNodes.pop(0)
def peelIter(self):
self.graph.ChkNodes.pop(0)
graph1=graph_main **#creating a new object identical to graph_main?**实际上是创建了一个指向graph_main所引用的对象的第二个引用。现在这两个变量都指向同一个对象。如果你需要一个单独的实例，你需要编写.copy()方法或类似方法来允许你克隆你的对象。 - Kirk Strauser