I'm getting a random ordered dict every time I compile, even using ordered dict. Im using dictionary to represent trees so its important to respect the order of the nodes. I had tried with python 3.6 and 3.7
class NP: #NounPhrase
def __init__(self, anchor = None, number = None):
self.anchor = anchor
self.number = number
class VP: #VerbPhrase
def __init__(self, anchor = None , person = None, tense = None):
self.person = person
self.tense = tense
self.anchor = anchor
class Tree:
def __init__(self, tree, sust = None, insert = None, anchor = None, terminal = None):
self.tree = tree
self.sust = sust
self.insert = insert
self.root = self.getRoot()
def getRoot(self):
return list(self.tree.keys())[0]
class TreeForest:
def makeIntransitiveVerb(text):
vp = VP(text)
return Tree( OrderedDict({ VP:{ NP , vp }}) )
verb = TreeForest.makeIntransitiveVerb("showed up")
print(verb.tree)
Expected result:
{< class '__main__.VP' > : { < class '__main__.NP' > , < __main__.VP object at 0x7f4b81fd8b90>}}
Actual results:
{< class '__main__.VP' >: {< __main__.VP object at 0x7f4b81fd8b90 >, < class '__main__.NP' >}})
Or
{< class '__main__.VP' >: { < class '__main__.NP' > , < __main__.VP object at 0x7f4b81fd8b90>}}
Related
I tried to make this implementation clear. So I created hasChild function of Node. But why am I getting this this error?
'NoneType' object has no attribute 'hasChild'
class Node():
def __init__(self,word):
self.value = str(word)
self.children = {}
self.isEndOfWord = False
def hasChild(self,ch):
return ch in self.children.keys()
def addChild(self,ch):
nodenew = Node(str(ch))
self.children[ch] = nodenew
def getChild(self,ch):
return self.children.get(ch)
class Trie():
def __init__(self):
self.root = Node('')
def insert(self,children):
current = self.root
for ch in children:
if (current.hasChild(ch) is False):
current.addChild(ch)
current = self.root.getChild(ch)
current.isEndOfWord = True
I changed current.hasChild(ch) is False into not current.hasChild(ch) and current = self.root.getChild(ch) into current = current.getChild(ch) of the insert function. It works. Thanks a lot!
class Node():
def __init__(self,word):
self.value = str(word)
self.children = {}
self.isEndOfWord = False
def hasChild(self,ch):
return ch in self.children.keys()
def addChild(self,ch):
nodenew = Node(ch)
self.children[ch] = nodenew
def getChild(self,ch):
return self.children.get(ch)
class Trie():
def __init__(self):
self.root = Node('')
def insert(self,children):
current = self.root
for ch in children:
if (not current.hasChild(ch)):
current.addChild(ch)
current = current.getChild(ch)
current.isEndOfWord = True
trie = Trie()
trie.insert('cat')
trie.insert('can')
I want to implements a-star algorithm and the function (from Route_Algorithm.py) extends the nodes to get the next layor of f_value in the tree . The node can be regard as the station. And the self.settings.station_matrix is the numpy.matrix.
def voluation_station(self, successor, dest_location,bus_stations):
'''initilize all the f(g+h) to the specific nodes'''
length = len(self.settings.station_matrix[successor])
for end_element in range(length):
for station in bus_stations:
if int(station.name) == end_element:
station.get_g(self.settings.station_matrix[successor][end_element])
length_station = len(self.settings.station_matrix[end_element])
for element_station in range(length_station):
if element_station == dest_location:
station.get_h(self.settings.station_matrix[end_element][dest_location])
for element in bus_stations:
element.result_f()
return bus_stations
However, when I run the part of code. It reports the error like this:
Traceback (most recent call last):
File "/home/surface/Final-Year-Project/FYP/Main.py", line 4, in <module>
class main():
File "/home/surface/Final-Year-Project/FYP/Main.py", line 13, in main
new_route.busy_route_matrix()
File "/home/surface/Final-Year-Project/FYP/oop_objects/Route.py", line 87, in busy_route_matrix
self.route_algorithm.A_STAR_Algorithm(start_location,dest_location,self.bus_stations)
File "/home/surface/Final-Year-Project/FYP/Util/Route_Algorithm.py", line 40, in A_STAR_Algorithm
self.voluation_station(successor, dest_location,bus_stations)
File "/home/surface/Final-Year-Project/FYP/Util/Route_Algorithm.py", line 73, in voluation_station
station.get_g(self.settings.station_matrix[successor][end_element])
TypeError: 'int' object is not callable
I search the solution in the Internet, I think the problem may be in the end_element, maybe some inherient problem but I'm not sure. Can some one help me! Please!
Additional codes for other classes:
These classes are Util classes, which helps for handle oop_objects!
The class is for the Route_Algorithm:
from Util.Mergesort_algorithm import mergesort_algorithm
class route_algorithm():
'''generate the route to optimise the profiles'''
def __init__(self,settings):
# a* algorithm
self.open_list = []
self.close_list = []
self.route = []
self.settings = settings
self.flag_find = False
self.lines = []
# merge_sort algorithm
self.mergesort_algorithm = mergesort_algorithm()
def A_STAR_Algorithm(self, start_location, dest_location,bus_stations):
'''search the best route for each passenger to the destination'''
#self.clean_f(bus_stations)
# initial the value of f in start_location
for item in bus_stations:
if int(item.name) == start_location:
item.get_g = 0
for key, value in item.adjacent_station.items():
if int(key.name) == dest_location:
item.get_h = value
self.open_list.append(start_location)
#start_location is the name of station
while self.flag_find == False:
successor = self.open_list[0]
self.open_list.remove(successor)
self.route.append(successor)
self.voluation_station(successor, dest_location,bus_stations)
self.a_brain_judge_1(dest_location,bus_stations)
print(self.flag_find)
if self.flag_find == True:
#end the location
self.route.append(dest_location)
#add the line to the self.line
self.print_lines()
self.flag_find = False
self.open_list = []
else:
#continue to search the minimize
list = self.sort(bus_stations)
for item in list:
print(item.name)
print(item.f)
#疑问如果前两个的预估值一样该如何处理
self.open_list.append(int(list[0].name))
def voluation_station(self, successor, dest_location,bus_stations):
'''initilize all the f(g+h) to the specific nodes'''
length = len(self.settings.station_matrix[successor])
for end_element in range(length):
for station in bus_stations:
if int(station.name) == end_element:
station.get_g(self.settings.station_matrix[successor][end_element])
length_station = len(self.settings.station_matrix[end_element])
for element_station in range(length_station):
if element_station == dest_location:
station.get_h(self.settings.station_matrix[end_element][dest_location])
for element in bus_stations:
element.result_f()
return bus_stations
def a_brain_judge_1(self, dest_location,bus_stations):
'''whether the direct_line is the optimize'''
tmp_dest = bus_stations[0]
self.tmp_nodes = []
self.flag_find = True
for element in bus_stations:
if int(element.name) == dest_location:
tmp_dest = element
for element in bus_stations:
if element == tmp_dest:
pass
else:
if element.f < tmp_dest.f:
self.tmp_nodes.append(element)
self.flag_find = False
if self.flag_find == True:
self.route.append(tmp_dest.name)
return None
else:
return self.tmp_nodes
def sort(self,bus_stations):
'''sort all the f in the next stations'''
return self.mergesort_algorithm.Merge_Sort(bus_stations)
def print_lines(self):
#print(len(self.route))
for item in self.route:
print(item)
print("NEXT PASSENGER!---------")
def clean_f(self,stations):
for item in stations:
item.clean_data()
The class is Random_Algorithm, which helps for generate the random passengers.
import random
from Data.Settings import settings
from oop_objects.Bus_Station import bus_station
from oop_objects.Passenger import passenger
class random_algorithm():
'''generate the random bus-stations and passengers'''
def __init__(self):
self.setting = settings()
def random_passenger(self,number):
'''generate random passengers for bus-station,
and assumes there are 6 stations now. Furthermore, the data will be crawled by the creeper'''
passengers = []
for i in range(number):
new_passenger = passenger()
random.seed(self.setting.seed)
new_passenger.Change_Name(random.randint(1,self.setting.bus_station_number))
# generate the start-location
self.setting.seed +=1
end_location = random.randint(1,self.setting.bus_station_number)
# generate the end-location
while new_passenger.name == end_location:
self.setting.seed += 1
end_location = random.randint(1,self.setting.bus_station_number)
#judge whether the start-location same as the end-location
new_passenger.change_end_location(end_location)
passengers.append(new_passenger)
return passengers
def random_station(self,number):
'''generate the name of random stations '''
bus_stations = []
for i in range(number):
new_bus_station = bus_station()
new_bus_station.Name(str(i))
bus_stations.append(new_bus_station)
return bus_stations
def random_edge(self,bus_stations):
'''generate the edge information for the stations'''
for location1 in bus_stations:
#print("The information add in "+location1.name)
for location2 in bus_stations:
if location1 != location2:
#print("the "+location2.name+" was added in the "+location1.name)
if location2 not in location1.adjacent_station and location1 not in location2.adjacent_station:
random.seed(self.setting.seed)
edge = random.randint(1,self.setting.edge_distance)
location1.add_adjacent_station(location2,edge)
#print("the edge is "+str(edge))
self.setting.seed += 1
return bus_stations
The class is the mergesort_algorithm, which compare the f for different stations
class mergesort_algorithm():
def Merge_Sort(self,stations):
length = len(stations)
middle = int(length/2)
if length<=1:
return stations
else:
list1 = self.Merge_Sort(stations[:middle])
list2 = self.Merge_Sort(stations[middle:])
return self.Merge(list1,list2)
def Merge(self,list1,list2):
list3 = []
length1 = len(list1)
length2 = len(list2)
point1 = 0
point2 = 0
while point1<=length1-1 and point2<=length2-1:
if list1[point1].f<list2[point2].f:
list3.append(list1[point1])
point1 += 1
else:
list3.append(list2[point2])
point2 += 1
if point1>=length1:
for i in range(length2):
if i>=point2:
list3.append(list2[point2])
if point2>=length2:
for i in range(length1):
if i>=point1:
list3.append(list1[point1])
return list3
#def print_sort_result(self):
The following class are oop.classes
The class is for the Route:
from Util.Random_Algorithm import random_algorithm
from Data.Settings import settings
from Util.Route_Algorithm import route_algorithm
import numpy as np
class route():
def __init__(self):
self.bus_stations = []
self.passengers = []
self.settings = settings()
#random algorithm
self.random_algorithm = random_algorithm()
#route_algorithm
self.route_algorithm = route_algorithm(self.settings)
def start_route(self):
'''The raw route Information(TEXT) for bus_stations '''
stations = self.random_algorithm.random_station(self.settings.bus_station_number)
finsih_edge_stations = self.random_algorithm.random_edge(stations)
'''
for item in finsih_edge_stations:
print("\nthe information for " + item.name + " is: \t")
for key, value in item.adjacent_station.items():
print("the station is " + key.name)
print(" the distace is " + str(value))
'''
self.bus_stations = finsih_edge_stations
'''The raw route Information(Text) for passengers'''
self.passengers = self.random_algorithm.random_passenger(self.settings.passengers_number)
def bus_stations_matrix(self):
'''trasfer the raw text to the matrix'''
#create zero_matrix
length = len(self.bus_stations)
tmp_matrix = np.zeros(length*length)
station_matrix = tmp_matrix.reshape(length,length)
for item in self.bus_stations:
for key,value in item.adjacent_station.items():
station_matrix[int(item.name)][int(key.name)] = value
station_matrix[int(key.name)][int(item.name)] = value
print(station_matrix)
self.settings.station_matrix = station_matrix
def passengers_matrix(self):
'''trasfer the raw text to the matrix'''
length = len(self.bus_stations)
tmp_matrix = np.zeros(length*length)
passenger_matrix = tmp_matrix.reshape(length,length)
for item in self.passengers:
#print("the start location of passenger is "+str(item.name))
#print("the end location of passenger is "+str(item.end_location))
#print(" ")
passenger_matrix[item.name-1][item.end_location-1]+=1;
print(passenger_matrix)
self.settings.passenger_matrix = passenger_matrix
def busy_route_matrix(self):
'''generate the bus_busy_route matrix'''
#read the requirements of passengers
length = self.settings.bus_station_number
for start_location in range(length):
for dest_location in range(length):
if self.settings.passenger_matrix[start_location][dest_location] == 0:
pass
else:
magnitude = self.settings.passenger_matrix[start_location][dest_location]
#运行a*算法去寻找最短路径/run the a* algorithm to search the path
self.route_algorithm.A_STAR_Algorithm(start_location,dest_location,self.bus_stations)
print("------------------------------------")
def practice(self):
'''practice some programming'''
for element in self.bus_stations:
print((element.f))
The class is for the Passenger
class passenger():
def __init__(self):
self.name = 0
self.end_location = "null"
def Change_Name(self,name):
'''change the name of passenger'''
self.name = name
def change_end_location(self,location):
'''generate the end_location'''
self.end_location = location
The class for the bus_station
class bus_station():
'''the class represents the bus station'''
def __init__(self):
'''the attribute of name means the name of bus-station
the attribute of passenger means the passenger now in the bus-station'''
self.name = "null"
self.passenger = []
self.adjacent_station = {}
#A* algorithm
self.g = 0
self.h = 0
self.f = 0
def Name(self,name):
'''change the name of the station'''
self.name = name
def add_passengers(self,*passenger):
'''add the passenger in the bus-station'''
self.passenger.append(passenger)
def add_adjacent_station(self,station,edge):
'''add the adjacent station in the this station'''
self.adjacent_station[station] = edge
def get_g(self,value):
'''get the value of g （线路值）'''
self.g =self.g+ value
def get_h(self,value):
'''get the value of f （预估值）'''
self.h = value
def result_f(self):
'''print the value of f （实际值）'''
self.f = self.g+self.h
def add_self_cost(self):
self.add_adjacent_station()
The following class is storing the data.
The class is for the setting:
class settings():
def __init__(self):
self.seed = 5
self.bus_station_number = 10
self.passengers_number = 10
self.edge_distance = 50
self.station_matrix = None
self.passenger_matrix = None
And the main class to run the whole project:
from oop_objects.Route import route
class main():
new_route = route()
new_route.start_route()
print("The distance between different bus station :")
new_route.bus_stations_matrix()
print("The location information for passengers :")
new_route.passengers_matrix()
new_route.busy_route_matrix()
#new_route.practice()practice
#new_route.sort()bus_stations
You should avoid the station of successor because you have assigned the value by using the get_g
The result should be:
def voluation_station(self, successor, dest_location,bus_stations):
'''initilize all the f(g+h) to the specific nodes'''
length = len(self.settings.station_matrix[successor])
for end_element in range(length):
if end_element == successor:
pass
else:
for station in bus_stations:
if int(station.name) == end_element:
station.get_g(self.settings.station_matrix[successor][end_element])
length_station = len(self.settings.station_matrix[end_element])
for element_station in range(length_station):
if element_station == dest_location:
station.get_h(self.settings.station_matrix[end_element][dest_location])
for element in bus_stations:
element.result_f()
return bus_stations
there are two functions: init and set_info. (full visison shown at the end)
class DefaultNode(object):
def __init__(self, node_name, node_pre= None, node_next = None,
act_func='sign', agg_func='sum', bias=0.0, response=1.0, node_type=None):
...
def set_info(self, node_pre= None, node_next = None, act_func='sign',
agg_func='sum', bias=0.0, response=1.0):
...
Set_info function has many default parameter values. I don't want to rewrite those parameters, which were given in the initializing process.In other words, if one of the parameter is to be set using set_info, the other parameters should remain the same.
For example,
temp_node = DefaultNode("givenname", node_pre = PRE)
temp_node.set_info("changedname")
the "node_pre" parameter of temp_node shall be "PRE" as initialized, instead of being replaced by the Default parameter in the function "set_info", i.e.
node_temp.node_pre != sign
the question is simple: how to implement it?
Thanks~
class DefaultNode(object):
def __init__(self, node_name, node_pre= None, node_next = None, act_func='sign', agg_func='sum', bias=0.0, response=1.0, node_type=None):
self.node_name = node_name
self.node_pre = node_pre
self.node_next = node_next
self.act_func_name = act_func
self.agg_func_name = agg_func
if act_func == "sign":
self.act_func = signmus_activation()
if agg_func == 'sum': # sign 和sum 是作为一个初始标记使用
self.agg_func = sum
self.bias = bias
self.response = response
self.node_type = node_type
def set_info(self, node_pre= None, node_next = None, act_func='sign', agg_func='sum', bias=0.0, response=1.0):
self.node_pre = node_pre
self.node_next = node_next
self.act_func_name = act_func
self.agg_func_name = agg_func
if act_func == "sign":
self.act_func = signmus_activation()
if agg_func == "sum":
self.agg_func = sum
self.bias = bias
self.response = response
EDIT 2: Updated my response after you clarified your question further (thanks!).
Option 1: You can use **kwargs and setattr to keep the parameter lists in sync. For example,
class Example(object):
def __init__(self):
self.first = 1
self.second = 2
def set_info(self, **kwargs):
for argument, value in kwargs.items():
if not hasattr(self, argument):
raise ValueError('invalid argument {}'.format(argument))
setattr(self, argument, value)
# Usage
e = Example()
print(e.first, e.second)
e.set_info(first=1000, second=2000)
print(e.first, e.second)
# This would raise an exception
# e.set_info(some_random_attribute='blah')
This outputs:
1 2
1000 2000
Option 2: Instead of having a separate method for setting fields, you could use #property and a corresponding setter for each. For example,
class Properties(object):
def __init__(self):
self._thing = 10
#property
def thing(self):
return self._thing
#thing.setter
def thing(self, t):
self._thing = t
# Usage
p = Properties()
print(p.thing)
p.thing = 20
print(p.thing)
Which prints
10
20
need a help with Dijkstra. I found a lot of codes on the internet, but I can't use any of them, because I'm not given a graph, but just lists of Vertexes & Edges into createGraph function. It's a homework and I gotta have some attributes in classes.
This is what I have:
class Vertex:
def __init__(self, id, name):
self.id = id
self.name = name
self.minDistance = float('inf')
self.previousVertex = None
self.edges = []
self.visited = False
class Edge:
def __init__(self, source, target, weight):
self.source = source
self.target = target
self.weight = weight
class Dijkstra:
def __init__(self):
self.vertexes = []
self.result = 0
def createGraph(self, vertexes, edgesToVertexes):
for i in range(len(vertexes)):
self.vertexes.append(vertexes[i])
for j in range(len(edgesToVertexes)):
if edgesToVertexes[j].source == vertexes[i].id:
vertexes[i].edges.append(edgesToVertexes[j])
def getVertexes(self):
return self.vertexes
def findMinID(self):
maxDistance = 1000000
curVertex = None
result = None
for i in range(len(self.vertexes)):
self.vertexes[i] = curVertex
if curVertex.visited is False and curVertex.minDistance < maxDistance:
curVertex = result
curVertex.minDistance = maxDistance
else:
pass
self.result = result
return
def computePath(self, sourceId):
start = None
end = None
road = None
while start is None:
if Vertex.id == sourceId:
start = Vertex
start.minDistance = 0
start.visited = True
for i in range(len(start.edges)):
start.edges[i].target = end
start.edges[i].weight = road
if road < end.minDistance:
end.minDistance = start.minDistance + road
end.previousVertex = start.id
else:
pass
self.findMinID()
self.computePath(self.result.id)
I'm still beginner so I tried to keep it simple, but it's not working as it raises error:
'type' object is not subscriptable
or:
AttributeError: type object 'Vertex' has no attribute 'id'
which makes absolutely no sense to me why.
I can use any help, thanks in advance!
When you put the line:
self.vertexes = Vertex
you are assigning the variable to the actual class. Probably what you wanted to do was make an empty list, as you append to it later:
self.vertexes = []
I would assume this is where the error comes from, as if you ever try to iterate over self.vertexes, you are iterating over the Vertex class, which is impossible and throws that error.
You also have later:
start = Vertex
Try initializing the start, like:
start = Vertex(sourceId, "vertex")
Also, the line before that you have
if Vertex.id == sourceId:
meaning that you might want to make the id variable in Vertex static:
class Vertex:
id = 0
def __init__(self, id, name):
self.id = id
id += 1
Some suggestions: class tutorial in python
Edit:
To find the vertex that has the id you want, use a filter:
start = None
for v in self.vertexes:
if v.id == sourceId:
start = Vertex(sourceId, v.name)
start.minDistance = 0
break
Here is my class:
class ManagementReview(object):
"""Class describing ManagementReview Object.
"""
# Class attributes
id = 0
Title = 'New Management Review Object'
fiscal_year = ''
region = ''
review_date = ''
date_completed = ''
prepared_by = ''
__goals = [] # List of <ManagementReviewGoals>.
__objectives = [] # List of <ManagementReviewObjetives>.
__actions = [] # List of <ManagementReviewActions>.
__deliverables = [] # List of <ManagementReviewDeliverable>.
__issues = [] # List of <ManagementReviewIssue>.
__created = ''
__created_by = ''
__modified = ''
__modified_by = ''
def __init__(self,Title='',id=0,fiscal_year='',region='',review_date='',
date_completed='',prepared_by='',created='',created_by='',
modified='',modified_by=''):
"""Instantiate object.
"""
if id:
self.setId(id)
if Title:
self.setTitle(Title)
if fiscal_year:
self.setFiscal_year(fiscal_year)
if region:
self.setRegion(region)
if review_date:
self.setReview_date(review_date)
if date_completed:
# XXX TODO: validation to see if date_completed pattern matches ISO-8601
self.setDate_completed(date_completed)
if prepared_by:
self.setPrepared_by(prepared_by)
if created:
# XXX TODO: validation to see if date_completed pattern matches ISO-8601
self.setCreated(created)
else:
self.setCreated(self.getNow())
if created_by:
self.setCreated_by(created_by)
self.__modified = self.getNow()
if modified_by:
self.__modified_by = modified_by
def __str__(self):
return "<ManagementReview '%s (%s)'>" % (self.Title,self.id)
def __setattr__(self, name, value): # Override built-in setter
# set the value like usual and then update the modified attribute too
object.__setattr__(self, name, value) # Built-in
self.__dict__['__modified'] = datetime.now().isoformat()
def getActions(self):
return self.__actions
def addAction(self,mra):
self.__actions.append(mra)
def removeAction(self,id):
pass # XXX TODO
I have this test:
from datetime import datetime
import random
import unittest
from ManagementReview import ManagementReview, ManagementReviewAction
# Default Values for ManagementReviewAction Object Type
DUMMY_ID = 1
DUMMY_ACTION = 'Action 1'
DUMMY_OWNER = 'Owner 1'
DUMMY_TITLE = 'Test MR'
DUMMY_FISCAL_YEAR = '2011'
DUMMY_REGION = 'WO'
DUMMY_REVIEW_DATE = '2009-01-18T10:50:21.766169',
DUMMY_DATE_COMPLETED = '2008-07-18T10:50:21.766169'
DUMMY_PREPARED_BY = 'test user'
DUMMY_CREATED = '2002-07-18T10:50:21.766169'
DUMMY_CREATED_BY = 'test user 2'
DUMMY_MODIFIED = datetime.now().isoformat()
DUMMY_MODIFIED_BY = 'test user 3'
class TestManagementReviewSetAction(unittest.TestCase):
def setUp(self):
self.mr = ManagementReview(DUMMY_TITLE,DUMMY_ID,fiscal_year=DUMMY_FISCAL_YEAR,region=DUMMY_REGION,
review_date=DUMMY_REVIEW_DATE,date_completed=DUMMY_DATE_COMPLETED,
prepared_by=DUMMY_PREPARED_BY,created=DUMMY_CREATED,
created_by=DUMMY_CREATED_BY,modified=DUMMY_MODIFIED,
modified_by=DUMMY_MODIFIED_BY)
def tearDown(self):
self.mr = None
def test_add_action(self):
for i in range(1,11):
mra = ManagementReviewAction(i,'action '+str(i),'owner '+str(i))
self.mr.addAction(mra)
self.assertEqual(len(self.mr.getActions()),10)
def test_remove_action(self):
print len(self.mr.getActions())
for i in range(1,11):
mra = ManagementReviewAction(i,'action '+str(i),'owner '+str(i))
self.mr.addAction(mra)
self.mr.removeAction(3)
self.assertEqual(len(self.mr.getActions()),9)
if __name__ == '__main__':
unittest.main()
The first test passes. That is, self.mr.getActions() has 10 actions.
However, when I run the 2nd test, test_remove_action, the value for len(self.mr.getActions()) is 10. At this point, though, it should be 0.
Why is this?
Thanks
see if you are keeping track of actions in a class attribute of ManagementReview as opposed to an instance attribute
A class attribute will be something like
class Spam(object):
actions = []
and an instance attribute will look something like
class Spam(object):
def __init__(self):
self.actions = []
What happens is that actions = [] is executed when the class is created and all instances of the class share the same list.
EDIT:
In light of your update, I can see that this is definitely what is going on