We Keep Coding

Is there a way to grab list attributes that have been initialized using self and append data to them in Python?

I have a class in Python that initializes the attributes of an environment. I am attempting to grab the topographyRegistry attribute list of my Environment class in a separate function, which when called, should take in the parameters of 'self' and the topography to be added. When this function is called, it should simply take an argument such as addTopographyToEnvironment(self, "Mountains") and append it to the topographyRegistry of the Environment class.
When implementing what I mentioned above, I ran into an error regarding the 'self' method not being defined. Hence, whenever I call the above line, it gives me:
print (Environment.addTopographyToEnvironment(self, "Mountains"))
^^^^
NameError: name 'self' is not defined
This leads me to believe that I am unaware of and missing a step in my implementation, but I am unsure of what that is exactly.
Here is the relevant code:
class EnvironmentInfo:
def __init__(self, perceivableFood, perceivableCreatures, regionTopography, lightVisibility):
self.perceivableFood = perceivableFood
self.perceivableCreatures = perceivableCreatures
self.regionTopography = regionTopography
self.lightVisibility = lightVisibility
class Environment:
def __init__(self, creatureRegistry, foodRegistry, topographyRegistery, lightVisibility):
logging.info("Creating new environment")
self.creatureRegistry = []
self.foodRegistry = []
self.topographyRegistery = []
self.lightVisibility = True
def displayEnvironment():
creatureRegistry = []
foodRegistry = []
topographyRegistery = ['Grasslands']
lightVisibility = True
print (f"Creatures: {creatureRegistry} Food Available: {foodRegistry} Topography: {topographyRegistery} Contains Light: {lightVisibility}")
def addTopographyToEnvironment(self, topographyRegistery):
logging.info(
f"Registering {topographyRegistery} as a region in the Environment")
self.topographyRegistery.append(topographyRegistery)
def getRegisteredEnvironment(self):
return self.topographyRegistry
if __name__ == "__main__":
print (Environment.displayEnvironment()) #Display hardcoded attributes
print (Environment.addTopographyToEnvironment(self, "Mountains"))#NameError
print (Environment.getRegisteredEnvironment(self)) #NameError
What am I doing wrong or not understanding when using 'self'?
Edit: In regard to omitting 'self' from the print statement, it still gives me an error indicating a TypeError:
print (Environment.addTopographyToEnvironment("Mountains"))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: Environment.addTopographyToEnvironment() missing 1 required positional argument: 'topographyRegistery'

Comments
Despite having def getRegisteredEnvironment(self): it wasn't indented, so it's not recognized as a class method.
self is a keyword used in conjunction with classes (class methods or attributes) - not functions. self is implied to be the instantiated object (eg a = Environment(...) -> self would refer to a) or the module's (I can't think of the proper term) class.
You didn't have your addTopographyToEnvironment class method defined.
In terms of your Environment class, you aren't using the variables you are passing to the class, so I made that change as well - I don't know if that was intentional or not.
As per your comment from the other answer, if you had def my_class_method(self) and you try to invoke it through an object with additional parameters, like so a = my_object(); a.my_class_method("Mountains"), you should get an error of the sorts, "2 positional arguments passed, expected 1.".
Your main problem is that you are doing Environment.class_method() and not creating an object from the class. Do a = Environment(whatever arguments here) to create an object from the class, then do a.addTopographyToEnvironment("Mountains") to do what you were going to do with "Mountains" and that object. What you have currently may be right, its just is missing the proper implementation, but the below article does a great job explaining the differences between all of them (Class Methods vs Static Methods vs Instance Methods), and is definitely worth the read.
class EnvironmentInfo:
def __init__(self, perceivableFood, perceivableCreatures, regionTopography, lightVisibility):
self.perceivableFood = perceivableFood
self.perceivableCreatures = perceivableCreatures
self.regionTopography = regionTopography
self.lightVisibility = lightVisibility
class Environment:
def __init__(self, creatureRegistry, foodRegistry, topographyRegistery, lightVisibility):
logging.info("Creating new environment")
self.creatureRegistry = creatureRegistry
self.foodRegistry = foodRegistry
self.topographyRegistery = topographyRegistery
self.lightVisibility = lightVisibility
def displayEnvironment(self):
creatureRegistry = []
foodRegistry = []
topographyRegistery = ['Grasslands']
lightVisibility = True
print (f"Creatures: {creatureRegistry} Food Available: {foodRegistry} Topography: {topographyRegistery} Contains Light: {lightVisibility}")
def addTopographyToEnvironment(self, environment):
return "Whatever this is supposed to return." + environment
def getRegisteredEnvironment(self):
return self.topographyRegistry
if __name__ == "__main__":
print (Environment.displayEnvironment()) #Display hardcoded attributes
print (Environment.addTopographyToEnvironment("Mountains"))#NameError
print (Environment.getRegisteredEnvironment()) #NameError
Object Instantiation In Python
With all that out of the way, I will answer the question as is posed, "Is there a way to grab list attributes that have been initialized using self and append data to them in Python?". I am assuming you mean the contents of the list and not the attributes of it, the attributes would be "got" or at least printed with dir()
As a simple example:
class MyClass:
def __init__(self, my_list):
self.my_list = my_list
if __name__ == "__main__":
a = MyClass([1, 2, 3, 4, 5])
print(a.my_list)
# will print [1, 2, 3, 4, 5]
a.my_list.append(6)
print(a.my_list)
# will print [1, 2, 3, 4, 5, 6]
print(dir(a.my_list))
# will print all object methods and object attributes for the list associated with object "a".
Sub Classing In Python
Given what you have above, it looks like you should be using method sub classing - this is done with the keyword super. From what I can guess, it would look like you'd implement that kind of like this:
class EnvironmentInfo:
def __init__(self, perceivableFood, perceivableCreatures, regionTopography, lightVisibility):
self.perceivableFood = perceivableFood
self.perceivableCreatures = perceivableCreatures
self.regionTopography = regionTopography
self.lightVisibility = lightVisibility
class Environment(EnvironmentInfo):
def __init__(self, creatureRegistry, foodRegistry, topographyRegistery, lightVisibility, someOtherThingAvailableToEnvironmentButNotEnvironmentInfo):
logging.info("Creating new environment")
super.__init__(foodRegistry, creatureRegistry, topographyRegistery, lightVisibility)
self.my_var1 = someOtherThingAvailableToEnvironmentButNotEnvironmentInfo
def displayEnvironment(self):
creatureRegistry = []
foodRegistry = []
topographyRegistery = ['Grasslands']
lightVisibility = True
print (f"Creatures: {creatureRegistry} Food Available: {foodRegistry} Topography: {topographyRegistery} Contains Light: {lightVisibility}")
def addTopographyToEnvironment(self, environment):
return "Whatever this is supposed to return." + environment
def getRegisteredEnvironment(self):
return self.topographyRegistry
def methodAvailableToSubClassButNotSuper(self)
return self.my_var1
if __name__ == "__main__":
a = Environment([], [], [], True, "Only accessible to the sub class")
print(a.methodAvailableToSubClassButNotSuper())
as the article describes when talking about super(), methods and attributes from the super class are available to the sub class.
Extra Resources
Class Methods vs Static Methods vs Instance Methods - "Difference #2: Method Defination" gives an example that would be helpful I think.
What is sub classing in Python? - Just glanced at it; probably an okay read.

Self represents the instance of the class and you don't have access to it outside of the class, by the way when you are calling object methods of a class you don't need to pass self cause it automatically be passed to the method you just need to pass the parameters after self so if you want to call an object method like addTopographyToEnvironment(self, newVal) you should do it like:
Environment.addTopographyToEnvironment("Mountains")
and it should work fine

How to print actual name of variable class type in function?

I'm trying to return variable name, but i keep getting this:
<classes.man.man object at (some numbers (as example:0x03BDCA50))>
Below is my code:
from classes.man import man
def competition(guy1, guy2, counter1=0, counter2=0):
.......................
some *ok* manipulations
.......................
if counter1>counter2:
return guy1
bob = man(172, 'green')
bib = man(190, 'brown')
print(competition(bob , bib ))
Epilogue
If anyone want to, explain please what I can write instead of __class__ in example below to get variable name.
def __repr__(self):
return self.__class__.__name__
Anyway, thank you for all of your support

There are different ways to approach your problem.
The simplest I can fathom is if you can change the class man, make it accept an optional name in its __init__ and store it in the instance. This should look like this:
class man:
def __init__(number, color, name="John Doe"):
self.name = name
# rest of your code here
That way in your function you could just do with:
return guy1.name
Additionnally, if you want to go an extra step, you could define a __str__ method in your class man so that when you pass it to str() or print(), it shows the name instead:
# Inside class man
def __str__(self):
return self.name
That way your function could just do:
return guy1
And when you print the return value of your function it actually prints the name.
If you cannot alter class man, here is an extremely convoluted and costly suggestion, that could probably break depending on context:
import inspect
def competition(guy1, guy2, counter1=0, counter2=0):
guy1_name = ""
guy2_name = ""
for name, value in inspect.stack()[-1].frame.f_locals.items():
if value is guy1:
guy1_name = name
elif value is guy2:
guy2_name = name
if counter1 > counter2:
return guy1_name
elif counter2 > counter2:
return guy1_name
else:
return "Noone"

Valentin's answer - the first part of it at least (adding a name attribute to man) - is of course the proper, obvious solution.
Now wrt/ the second part (the inspect.stack hack), it's brittle at best - the "variables names" we're interested in might not necessarily be defined in the first parent frame, and FWIW they could as well just come from a dict etc...
Also, it's definitly not the competition() function's responsability to care about this (don't mix domain layer with presentation layer, thanks), and it's totally useless since the caller code can easily solve this part by itself:
def competition(guy1, guy2, counter1=0, counter2=0):
.......................
some *ok* manipulations
.......................
if counter1>counter2:
return guy1
def main():
bob = man(172, 'green')
bib = man(190, 'brown')
winner = competition(bob, bib)
if winner is bob:
print("bob wins")
elif winner is bib:
print("bib wins")
else:
print("tie!")

Python prints the location of class objects in memory if they are passed to the print() function as default. If you want a prettier output for a class you need to define the __repr__(self) function for that class which should return a string that is printed if an object is passed to print(). Then you can just return guy1

__repr__ is the method that defines the name in your case.
By default it gives you the object type information. If you want to print more apt name then you should override the __repr__ method
Check below code for instance
class class_with_overrided_repr:
def __repr__(self):
return "class_with_overrided_repr"
class class_without_overrided_repr:
pass
x = class_with_overrided_repr()
print x # class_with_overrided_repr
x = class_without_overrided_repr()
print x # <__main__.class_without_overrided_repr instance at 0x7f06002aa368>
Let me know if this what you want?

dynamic instances of a class object overwriting each other

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.

Trying to build trie with classes in python - strange behavior

I'm trying to implement trie in python. I'm using dictionaries+classes instead of lists (I know it's not optimal, but I'm just trying to make it work at all).
After debugging I found out that each layer has all letters in dictionary. I cannot understand why.
Here is my code (implementation is 100% most basic, straightforward):
class lttr:
finish = 0
pointers = {} #for letters to reference class instance
eps = lttr()
def add(word):
global eps
last = eps
for ind,x in enumerate(word):
if last.pointers.get(x,None):
last = last.pointers[x]
else:
last.pointers[x] = lttr()
last=last.pointers[x]
last.finish=1
def lookup(word):
global eps
last=eps
for ind,x in enumerate(word):
if last.pointers.get(x,None):
last=last.pointers[x]
else:
return False
return bool(last.finish)
add("pear")
print lookup("ar") #prints True ... but why?

I'm guessing you intended for each individual lttr instance to have its own unique values for finish and pointers. In which case, you need to declare them as attributes of self inside __init__, rather than just defining them at the class scope.
class lttr:
def __init__(self):
self.finish = 0
self.pointers = {} #for letters to reference class instance
Now your script will print False as expected.

Your lttr class has class variables, but you want instance variables. Class variables are unique across all instances of that class, so you only have one pointers object.
class lttr:
finish = 0
pointers = {} #for letters to reference class instance
What you want is
class lttr:
def __init__(self):
self.finish = 0
self.pointers = {}
and that works as expected.

Using getattr to work with a method from another class

pI am working on a bit of code that does nothing important, but one of the things I am trying to make it do is call a function from another class, and the class name is pulled out of a list and put into a variable. Mind you I have literally just learned python over the last 2 weeks, and barely know my way around how to program.
What I believe that this should do is when getattr() is called, it will pass the attribute 'run_question' that is contained in the respective class with the same name as what is in question_type, and then pass it onto 'running_question'. I know there are probably better ways to do what I am attempting, but I want to know why this method doesn't work how I think it should.
#! /usr/bin/python
rom random import randrange
class QuestionRunner(object):
def __init__(self):
##initialize score to zero
self.score = 0
##initialize class with the types of questions
self.questiontypes = ['Addition', 'Subtraction', 'Division', 'Multiplication']
##randomly selects question type from self.questiontypes list
def random_type(self):
type = self.questiontypes[randrange(0, 4)]
return type
##question function runner, runs question function from self
def run_questions(self):
try:
question_type = self.random_type()
running_question = getattr(question_type, 'run_question' )
except AttributeError:
print question_type
print "Attribute error:Attribute not found"
else: running_question()
class Question(object):
pass
class Multiplication(Question):
def run_question(self):
print "*"
class Division(Question):
def run_question(self):
print "/"
class Subtraction(Question):
def run_question(self):
print "-"
class Addition(Question):
def run_question(self):
print "+"
test = QuestionRunner()
test.run_questions()
This outputs:
[david#leonid mathtest] :( $ python mathtest.py
Division
Attribute error:Attribute not found
[david#leonid mathtest] :) $
Which indicates that I am not getting the run_question attribute as I expect.
I should note that when I put the functions into the QuestionRunner class in the following way, everything works as expected. The main reason I am using classes where it really isn't needed it to actually get a good grasp of how to make them do what I want.
#! /usr/bin/python
from random import randrange
class QuestionRunner(object):
def __init__(self):
##initialize score to zero
self.score = 0
##initialize class with the types of questions
self.questiontypes = ['addition', 'subtraction', 'division', 'multiplication']
##randomly selects question type from self.questiontypes list
def random_type(self):
type = self.questiontypes[randrange(0, 4)]
return type
##question function runner, runs question function from self
def run_questions(self):
try:
question_type = self.random_type()
running_question = getattr(self, question_type)
except AttributeError:
exit(1)
else: running_question()
def multiplication(self):
print "*"
def division(self):
print "/"
def addition(self):
print "+"
def subtraction(self):
print "-"
test = QuestionRunner()
test.run_questions()
Any help on why this isn't working would be great, and I appreciate it greatly.
Any help on why this isn't working would be great, and I appreciate it greatly.

Ah, I have found out the missing concept that was causing my logic to be faulty. I assumed that I could pass the name of an object to getattr, when in reality I have to pass the object itself.