I have a python class called Player that looks like this ...
class Player:
def __init__(self):
self.display = 'A'
self.num_water_buckets = 0
self.row = 0
self.col = 0
I am having trouble editing the self.row and self.col ... maybe they're immutable but I haven't found much of this on the internet. Player().row and Player().col work, however they print 0 every time. I am trying to edit them using Player().row = value where value is a variable containing a number.
Thanks in advance!
UPDATE: Okay so I understand that you have to define a new occurrence of this instance using x = Player() then x.row = ...
But I need to originally initialise the variable with certain values (which are different every time) so I thought I could use a function and the return value from that function would set the initial value from the variable but it just creates an infinite recursion.
I did...
class Player:
def __init__(self):
from game_parser import read_lines
self.display = 'A'
self.num_water_buckets = 0
self.row = Player().detRow(sys.argv[1])
self.col = Player().detCol(sys.argv[1])
def detRow(fileName):
# use this function to return the row
def detCol(fileName):
# use this function to return the col
If you do
Player().row = value
print(Player().row)
The Player() in the first row creates a new instance; then you modify it by setting its row attribute to value; then you throw away that instance, because you haven't bothered to remember it anywhere. Then in the next row, you create a new instance (where the initialiser sets the row attribute to zero).
Not all players are interchangeable. If you sit John in the second row, it does not mean Harry will be in the second row too; it just means John is in the second row.
To do it correctly, store your Player instance in a variable:
john = Player()
john.row = 2
print(john.row)
You need to add put the variable outside the __init__() method
EDIT: added row and col to the class
class Player:
row = 0 # NO self here
col = 0
def __init__(self):
self.display = 'A'
self.num_water_buckets = 0
john = Player()
john.num_water_buckets = 12
print(f'before change: {john.col}')
john.col = 5
print(f'after change: {john.col}')
print(f'class property: {Player.col}') # note it did not change the class
Output:
before change: 0
after change: 5
class property: 0
Related
If I were to have these functions in a class, how would I call them from another function in the same class?
class Dead:
def initial(self):
self.amy = 1
self.bob = 2
self.cam = 3
def __init__(self):
self.initial()
def get_number(self, number):
How could I call self.amy, and in return be getting the number 1? In get_number I would like to add like self.amy to a number to return the sum, but like with all amy, bob, cam in one go with a for function maybe? I'm not sure how to word this question without completely spoiling the question, sorry.
You could change your get_number method to accept a member variable name instead and dynamically retrieve it. E.g.
class Dead:
def initial(self):
self.amy = 1
self.bob = 2
self.cam = 3
def __init__(self):
self.initial()
def get_number(self, name, number):
return getattr(self, name) + number
However, this is more than redundant. You can already access those variables from your object, adding a method to access them is adding an extra layer for no reason.
class Dead:
def initial(self):
self.amy = 1
self.bob = 2
self.cam = 3
def __init__(self):
self.initial()
dead = Dead()
dead.amy # 1
dead.bob # 2
dead.cam # 3
dead.amy += 1 # 2
So is adding an initial method to initialize your member variables. No reason not to do so inside your __init__ directly.
class Dead:
def __init__(self):
self.amy = 1
self.bob = 2
self.cam = 3
Adding useless methods is not making your code better, it really just pollute it.
I have a function that creates a player object but when referencing the object, I get a NameError. I think it is happening due to local scope but global should fix it...
I just started out OOP and this code is working in the python shell but it is not working in script mode.
endl = lambda a: print("\n"*a)
class Score:
_tie = 0
def __init__(self):
self._name = ""
self._wins = 0
self._loses = 0
def get_name(self):
print
self._name = input().upper()
def inc_score(self, wlt):
if wlt=="w": self._wins += 1
elif wlt=="l": self._loses += 1
elif wlt=="t": _tie += 1
else: raise ValueError("Bad Input")
def player_num(): #Gets number of players
while True:
clear()
endl(10)
print("1 player or 2 players?")
endl(5)
pnum = input('Enter 1 or 2: '.rjust(55))
try:
assert int(pnum) == 1 or int(pnum) == 2
clear()
return int(pnum)
except:
print("\n\nPlease enter 1 or 2.")
def create_player(): #Creates players
global p1
p1 = Score()
yield 0 #stops here if there is only 1 player
global p2
p2 = Score()
def pr_(): #testing object
input(p1._wins)
input(p2._wins)
for i in range(player_num()):
create_player()
input(p1)
input(p1._wins())
pr_()
wherever I reference p1 I should get the required object attributes but I'm getting this error
Traceback (most recent call last):
File "G:/Python/TicTacTwo.py", line 83, in <module>
input(p1)
NameError: name 'p1' is not defined
Your issue is not with global but with the yield in create_player(), which turns the function into a generator.
What you could do:
Actually run through the generator, by executing list(create_player()) (not nice, but works).
But I suggest you re-design your code instead, e.g. by calling the method with the number of players:
def create_player(num): #Creates players
if num >= 1:
global p1
p1 = Score()
if num >= 2:
global p2
p2 = Score()
If you fix this issue, the next issues will be
1) input(p1) will print the string representation of p1 and the input will be lost, you probably want p1.get_name() instead.
2) input(p1._wins()) will raise TypeError: 'int' object is not callable
I will redesign the app to introduce really powerful python constructs that may help you when getting into OOP.
Your objects are going to represent players, then don't call them Score, call them Player.
Using _tie like that makes it a class variable, so the value is shared for all the players. With only two participants this may be true but this will come to hurt you when you try to extend to more players. Keep it as a instance variable.
I am a fan of __slots__. It is a class special variable that tells the instance variables what attributes they can have. This will prevent to insert new attributes by mistake and also improve the memory needed for each instance, you can remove this line and it will work but I suggest you leave it. __slots__ is any kind of iterable. Using tuples as they are inmutable is my recomendation.
Properties are also a really nice feature. They will act as instance attribute but allow you to specify how they behave when you get the value (a = instance.property), assign them a value (instance.property = value), or delete the value (del instance.property). Name seems to be a really nice fit for a property. The getter will just return the value stored in _name, the setter will remove the leading and trailing spaces and will capitalize the first letter of each word, and the deletter will set the default name again.
Using a single function to compute a result is not very descriptive. Let's do it with 3 functions.
The code could look like this:
# DEFAULT_NAME is a contant so that we only have to modify it here if we want another
# default name instead of having to change it in several places
DEFAULT_NAME = "Unknown"
class Player:
# ( and ) are not needed but I'll keep them for clarity
__slots__ = ("_name", "_wins", "_loses", "_ties")
# We give a default name in case none is provided when the instance is built
def __init__(self, name=DEFAULT_NAME):
self._name = name
self._wins = 0
self._loses = 0
self._ties = 0
# This is part of the name property, more specifically the getter and the documentation
#property
def name(self):
""" The name of the player """
return self._name
# This is the setter of the name property, it removes spaces with .strip() and
# capitalizes first letters of each word with .title()
#name.setter
def name(self, name):
self._name = name.strip().title()
# This is the last part, the deleter, that assigns the default name again
#name.deleter
def name(self):
self._name = DEFAULT_NAME
def won(self):
self._wins += 1
def lost(self):
self._loses += 1
def tied(self):
self._ties += 1
Now that's all we need for the player itself. The game should have a different class where the players are created.
class Game:
_min_players = 1
_max_players = 2
def __init__(self, players):
# Check that the number of players is correct
if not(self._min_players <= players <= self._max_players):
raise ValueError("Number of players is invalid")
self._players = []
for i in range(1, players+1):
self._players.append(Player(input("Insert player {}'s name: ".format(i))))
#property
def players(self):
# We return a copy of the list to avoid mutating the inner list
return self._players.copy()
Now the game would be created as follows:
def new_game():
return Game(int(input("How many players? ")))
After that you would create new methods for the game like playing matches that will call the players won, lost or tied method, etc.
I hope that some of the concepts introduced here are useful for you, like properties, slots, delegating object creation to the owner object, etc.
This question already has answers here:
How to avoid having class data shared among instances?
(7 answers)
Closed 3 years ago.
I've the following class structure:
class StarCount:
one_stars = 0
two_stars = 0
three_stars = 0
four_stars = 0
five_stars = 0
class OrientationAnalysis:
straight = StarCount()
bisexual = StarCount()
gay = StarCount()
class GenderAnalysis:
men = OrientationAnalysis()
women = OrientationAnalysis()
I've written the following code:
genderanalysis = GenderAnalysis()
genderanalysis.men.straight.five_stars = 100
print genderanalysis.men.straight.five_stars # outputs 100
print genderanalysis.women.straight.five_stars # this is also 100
Why genderanalysis.women.straight.five_stars is also updated? I've checked the genderanalysis.women.gay.five_stars also but it's not updated?
When you declare some variables like this:
class StarCount:
one_stars = 0
two_stars = 0
three_stars = 0
four_stars = 0
five_stars = 0
These variables become class variables. Class variables are variables that are shared by all instances of a class. So when you updated genderanalysis.men.straight.five_stars, it actually updated StarCount.five_stars and as genderanalysis.women.straight.five_stars also points to the same variable, it seemed to have updated too.
I think what you are looking for are instance variables. You can declare them like this:
class StarCount:
def __init__(self):
self.one_stars = 0
self.two_stars = 0
self.three_stars = 0
self.four_stars = 0
self.five_stars = 0
Edit
Why genderanalysis.women.gay.five_stars is not updated?
What happens is that before you updated any variable of genderanalysis object, all of the variables were pointing to the variables of StarCount class. As you can see they have same id:
print(id(StarCount.five_stars)) # prints '94016229389744'
print(id(genderanalysis.men.straight.five_stars)) # prints '94016229389744'
print(id(genderanalysis.women.gay.five_stars)) # prints '94016229389744'
But when you changed genderanalysis.men.straight.five_stars, the reference/pointer got replaced with your provided value, in this case 100. You can see difference in their id's:
print(id(StarCount.five_stars)) # prints '94016229389744'
print(id(genderanalysis.men.straight.five_stars)) # prints '94016229391328', see the difference?
So now genderanalysis.men.straight.five_stars does not point to StarCount.five_stars, rather it points to OrientationAnalysis.straight.five_stars. Once again, let's check their id's:
print(id(OrientationAnalysis.straight.five_stars)) # prints '94016229391328'
print(id(genderanalysis.men.straight.five_stars)) # prints '94016229391328', same right?
Now onto your question, at this point genderanalysis.women.gay.five_stars is still untouched so it points to StarCount.five_stars and so it still prints 0. Change StarCount.five_stars and you can see the change reflecting in genderanalysis.women.gay.five_stars.
StarCount.five_stars = 101
print(genderanalysis.women.gay.five_stars) # prints `101`
Define the values in the init methods of the classes, so that they become attached to intance objects, not the class object itself.
class StarCount:
def __init__(self):
self.one_stars = 0
self.two_stars = 0
self.three_stars = 0
self.four_stars = 0
self.five_stars = 0
class OrientationAnalysis:
def __init__(self):
self.straight = StarCount()
self.bisexual = StarCount()
self.gay = StarCount()
class GenderAnalysis:
def __init__(self):
self.men = OrientationAnalysis()
self.women = OrientationAnalysis()
genderanalysis = GenderAnalysis()
genderanalysis.men.straight.five_stars = 100
print genderanalysis.men.straight.five_stars # outputs 100
print genderanalysis.women.straight.five_stars # this is now 0
your attributes should not be class attributes but instance attributes instead. this would be a start for you:
class StarCount:
def __init__(self, five_stars=0):
self.five_stars = five_stars
# ...
class OrientationAnalysis:
def __init__(self):
self.straight = StarCount()
# ...
class GenderAnalysis:
def __init__(self):
self.men = OrientationAnalysis()
self.women = OrientationAnalysis()
you’re almost there— you are referencing and modifying class variables rather than instance variables.
You need an __init__(self) method, and to create all the attributes on self
I have a simple class that stores simple data. The class is as follows.
class DataFormater:
def __init__(self, N, P, K, price):
self.N = N
self.P = P
self.K = K
self.price = price
The code that calls this class is
from DataFormater import DataFormater
#global variables
ObjectList = [0,1,2,3,4,5,6,7,8,9,10,
11,12,13,14,15,16,17,18,19,20,
21,22,23,24,25,26,27,28,29,30,
31,32,33,34,35,36,37,38,39,40,
41,42,43,44,45,46,47,48,49,50]
ObjectListCounter = 0
# main
print "enter you N-P-K values, followed by a coma, then the price"
print "example ----> 5 5 5 %50 "
print "return as many values as you want to sort, then enter, 'done!' when done."
while True:
RawData = raw_input()
if RawData == 'done!':
break
else:
ObjectList[ObjectListCounter] = DataFormater
ObjectList[ObjectListCounter].N = int(RawData[0])
# very simple test way of putting first indice in ObjectList[ObjectListCounter].N
ObjectListCounter += 1
print ObjectList[0].N
print ObjectList[1].N
My idea is that ObjectList[0] would create that object '1' that I could call with 1.N
But, when I call these, it seems that I have overwritten the previous instances.
this is what prints...
return as many values as you want to sort, then enter, 'done!' when done.
12
1
done!
1
1
Thanks so much! And I know that my post is messy, I don't exactly know how to make it more "pretty"
So, it looks like you are assigning the actual class (instead of an instance of the class) in your loop. Where you do this:
ObjectList[ObjectListCounter] = DataFormater
I think what you actually want is this
ObjectList[ObjectListCounter] = DataFormater(...insert args here....)
EDIT to address the comments:
Your class init method looks like this:
def __init__(self, N, P, K, price):
That means that to create an instance of your class, it would look like this:
my_formater = DataFormater(1, 2, 3, 4)
You would then be able to access my_formater.N which would have a value of 1.
What you are trying to do instead is access a CLASS level attribute, DataFormater.N. This is generally used in situations where you have a constant variable that does not change between instances of the class. For example:
class DataFormater():
CONSTANT_THING = 'my thing that is always the same for every instance'
You would then be able to access that variable directly from the class, like this:
DataFormater.CONSTANT_THING
I hope that clears things up.
I have the following tile class which got some instance variables such as UNMAPPED,FREE etc.
Those instance variables get a default value once new instance is created, but i want to set some of this variables from a method within the instance itself.
when im trying to do so, it seems the the new value is not saved but when im doing it without any method it seems to work.
How can it be?
class tile():
def __init__(self):
self.FREE = 0
self.UNMAPPED = 1
def set_tile(self,newVal):
self.FREE = newVal
so that :
tile1 = tile()
tile1.set_tile(20) -> tile1.FREE = 0
but,
tile1.FREE = 20 -> tile1.FREE = 20
thanks for your help