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Creating a Class and Objects [closed]

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I got an assignment. I have to create a class with objects. For example, the class Student. In this class I have to create certain students and then I have to assign these students to a set.
class Students:
def __init__(self, name, age):
self.name = name
self.age = age
def show_info(self):
return "'{}': {}".format(self.name, self.age)
def __str__(self):
return self.show_info()
Mark = Students(name="Mark", age=21)
Lisa = Students(name="Lisa", age=19)
So my question is how do I add these Objects(Mark,Lisa) to a set(). I'd be grateful if someone can give me some hints.

Assuming you want the class instances Mark and Lisa themselves to be added to a set, a simple way in Python 3 is to make use of dataclasses -- which are essentially just regular classes under the hood -- and pass the unsafe_hash parameter to the decorator, so that a __hash__ method is automatically generated for us, as shown below.
from dataclasses import dataclass
#dataclass(unsafe_hash=True)
class Student:
name: str
age: int
def show_info(self):
return "'{}': {}".format(self.name, self.age)
def __str__(self):
return self.show_info()
Mark = Student(name="Mark", age=21)
Lisa = Student(name="Lisa", age=19)
my_set = {Mark, Lisa}
print(my_set)
# If you want to customize how `Student` objects are displayed, implement
# a __repr__ instead of __str__, or just copy the implementation directly.
Student.__repr__ = Student.__str__
print(my_set)
Output:
{Student(name='Lisa', age=19), Student(name='Mark', age=21)}
{'Lisa': 19, 'Mark': 21}
If you want to add the instances attributes to a set instead, you can convert each instance to a tuple of its attributes and pass it into the set constructor instead, since tuples are immutable objects and are thus hashable. This is actually a great use-case for the astuple helper function which is exported by the dataclasses module.
from dataclasses import dataclass, astuple
#dataclass
class Student:
name: str
age: int
Mark = Student(name="Mark", age=21)
Lisa = Student(name="Lisa", age=19)
my_set = {astuple(Mark), astuple(Lisa)}
print(my_set)
Output:
{('Lisa', 19), ('Mark', 21)}
A simplification of the above concept is to use typing.NamedTuple instead of the dataclass approach. This allows you to retain the type hinting support and the ability to pass keyword arguments to the constructor method as in the original example, but also makes each class instance inherently hashable, since named tuples are essentially tuples under the hood. An example usage of NamedTuple is shown below:
from typing import NamedTuple
class Student(NamedTuple):
name: str
age: int
Mark = Student(name="Mark", age=21)
Lisa = Student(name="Lisa", age=19)
my_set = {Mark, Lisa}
print(my_set)
Output:
{Student(name='Lisa', age=19), Student(name='Mark', age=21)}

"def" bringing the wrong answer [closed]

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I made a class with some functions:
But when I instantiate the values the answer is bringing me 'alimentos', but that's wrong it should be 'portugues' .
I have two dictionaries and this class:
professores_x = {
'alimentos': [{"prof_id":"xx_alimento_1", "prof_disc":"alimentos"},
{"prof_id":"xx_alimento_2", "prof_disc":"alimentos"}],
'português': [{"prof_id":"xx_port_1", "prof_disc":"português"},
{"prof_id":"xx_port_2", "prof_disc":"português"}]}
courses_x = {'alimentos': [{"course_name":"padeiro_confeiteiro"},
{"course_name":"padeiro_confeiteiro"}]}
# trying refactoring
class Disciplinas_cursos_1:
"Define the disciplinas and professors"
def __init__(self,cursos_,professores_):
self.cursos_ = cursos_
self.professores_ = professores_
for self.p in self.cursos_.keys():
if self.p == 'alimentos': self.alimentos()
elif self.p == 'português': self.portugues()
def alimentos(self):
profiel_prof_disc = self.professores_[self.p][::]
prof_disc_al = self.p
discipl_alimentos = [self.p,[x['prof_id'] for x in profiel_prof_disc
if x['prof_disc'] == prof_disc_al]]
return discipl_alimentos
def portugues(self):
print("Now its portuguese turn")
profiel_prof_disc = self.professores_[self.p][::]
prof_disc_port = self.p
print(f"see I'm printing {prof_disc_port}. It's that the same of portuguese? If' not it's wrong")
discipl_port =[self.p,[x['prof_id'] for x in profiel_prof_disc if x['prof_disc'] ==prof_disc_port]]
print(f"see I'm printing {prof_disc_port} and {discipl_port}")
return discipl_port
# ok!! Now I do the instance:
disc_a = Disciplinas_cursos_1(courses_x, professores_x)
disc_a.alimentos()
Output
['alimentos', ['xx_alimento_1', 'xx_alimento_2']]
Nice, that is what I want but when I try the second function it's bring me 'alimentos'
but I need 'portugues' and not 'alimentos'.
disc_a.portugues()
Output
Now its portuguese turn
see I'm printing alimentos. It's that the same of portuguese? If' not it's wrong
see I'm printing alimentos and ['alimentos', ['xx_alimento_1', 'xx_alimento_2']]

Your issue is with self.p. In __init__, you're setting that value with your loop, and when you call self.alimentos() or self.portugues() in the body of the loop it will make sense since the self.p value will correspond to the method being called.
But if you call disc_a.portugues() from outside of __init__, you're going to get the last value self.p had after the loop, which may not match up at all with the method you're calling. That's why you're getting invalid output, it's using an inappropriate self.p key.
I don't have a firm understanding of what you're intending to do in your methods, so I don't really have a recommended fix. But in general, I'd suggest you think more carefully about which values you're passing to which parts of your code as attributes and as arguments. self.p should probably not exist as an attribute. Maybe it should be an argument to the methods? Maybe you need different attributes to sort your data into separate containers, rather than repeatedly looping over it all. You may need to redesign your class to have its data make more sense the way you need to use it.

Having the 'Tuple' has no attribute k [closed]

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So I created a set of libraries that makes it easier for me to track my LoL Stats over the course of the season, for that I have a class game:
class game:
def __init__(self,kills,deaths,assists,pos,champ,cs,tk,wl,length = time(0,20,0)):
self.k = kills
self.a = assists
self.d = deaths
self.l = length
self.p = pos
self.c = champ
self.cs = cs
self.tk = tk
self.wl = wl
and a class gl (GameList)
class gl:
def __init__(self):
self.ki = []
self.ass = []
self.de = []
self.ch = []
self.po = []
self.le = []
self.csc = []
self.tki = []
self.wil =[]
Now when I use the method self.add() in the gl class where g is an object of the class game:
def add(self,g):
self.ki.append(g.k)
self.ass.append(g.a)
self.de.append(g.d)
self.ch.append(g.c)
self.po.append(g.p)
l = g.l.traM()
self.le.append(l)
self.csc.append(g.cs)
self.tki.append(g.tk)
if game.wl == True:
self.wil.append("Win")
else:
self.wil.append("Loss")
I get the Error: AttributeError: 'tuple' object has no attribute 'k'
Now when I tried this earlier it worked fine and I have no Idea why it stopped working the only thing that change was that I installed matplotlib and used that to create a few methods involving piecharts.
I would be happy if someone could help me out and maybe provide a solution, since I am fairly new to python but programmed in Pascal before.

Since you're new to Python, if you haven't already met type() let me introduce you :-) The type() function will show you what something is. To troubleshoot your code try adding some print statements like this:
def add(self,g):
print('add() type(g)={}'.format(type(g)))
print('add() g={}'.format(g))
self.ki.append(g.k)
self.ass.append(g.a)
self.de.append(g.d)
Once you find out what kind of thing g is go ahead and edit your question and let us know. Like #Graipher says it is probably something different than you expect.
Once you get that working, from a design point of view it seems easier to keep a list of Game instances instead of a list of all the individual attributes.
class gl2:
def __init__(self):
self.games = [ ] # list to hold games
def __str__(self):
return 'gl2(#games={})'.format(len(self.games)))
def add(self, g):
self.games.add(g)
Adding __str__() methods can make it much easier to see what your classes are doing. You might want to add one to your game class, if nothing else just to make debugging easier:
class game:
def __str__(self):
return 'game(#kills={})'.format(len(self.k)))

Should a class to have several attributes or one attribute as dictionary with many keys, Python3

I have class for calculating temperatures of an object at different positions, based on ambient temperature. I have two ways of implementation. In BodyA, the temperature of each position is an attribute of the class; while in BodyB, there is an attribute pos_t, which is a dict, and the temperature of each position is just a key-value pair in the dict.
class BodyA:
def __init__(self, ambient_temperature)
self.amb_t = ambient_temperature
self.pos1_t = self.amb_t + 1
self.pos2_t = self.amb_t * 2
self.pos3_t = self.pos1_t + self.pos2_t - 5
class BodyB:
def __init__(self, ambient_temperature)
self.amb_t = ambient_temperature
self.pos_t = dict()
self.pos_t['pos1'] = self.amb_t + 1
self.pos_t['pos2'] = self.amb_t * 2
self.pos_t['pos3'] = self.pos_t['pos1'] + self.pos_t['pos2'] - 5
In practical case, there are up-to 10 positions, and I want to build child-class from it. And some child-classes do not have certain positions. For example, pos2 can be missing in some child.
Could you please let me know, which design is better in terms of OOP and efficiency. Thanks.

A data structure to store some custom identifiers that may or may exist calls clearly for a dict. As class attributes are also stored in an internal dict, the first approach can be used too, but to have pratical manipulation without explicit hand writing the members will require different code. I suspect performance will not matter. If you find it matters, maybe a redesign of the data structure that does not use classes at all will do, as object creation processing time may be relevant then.

Designing a black box python [closed]

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I want to have a black box in python where
The input is a list A.
There is a random number C for the black box which is randomly selected the first time the black box is called and stays the same for the next times the black box is called.
Based on list A and number C, the output is a list B.
I was thinking of defining this black box as a function but the issue is that a function cannot keep the selected number C for next calls. Note that the input and output of the black box are as described above and we cannot have C also as output and use it for next calls. Any suggestion?

Make it a Class so C will persist.
class BlackBox():
def __init__(self):
self.C = rand.randint(100)
etc...
As a side note, using some pretty cool Python functionality...
You can make objects of this class callable by implementing __call__() for your new class.
#inside the BlackBox class
def __call__(self, A):
B = []
#do something to B with A and self.C
return B
You can then use this in your main code.
bb = BlackBox()
A = [1, 2, 3]
B = bb(A)

the issue is that a function cannot keep the selected number C for next calls.
This may be true in other languages, but not so in Python. Functions in Python are objects like any other, so you can store things on them. Here's a minimal example of doing so.
import random
def this_function_stores_a_value():
me = this_function_stores_a_value
if 'value' not in me.__dict__:
me.value = random.random()
return me.value
This doesn't directly solve your list problem, but it should point you in the right direction.
Side note: You can also store persistent data in optional arguments, like
def this_function_also_stores_a_value(value = random.random()):
...
I don't, however, recommend this approach because users can tamper with your values by passing an argument explicitly.

There are many ways to store persistent data for a function. They all have their uses, but in general, the ones that come first are useful more often than the ones that come later. (To keep things shorter, I'm solving a slightly simpler problem than the one you asked about, but it should be obvious how to adapt it.)
Instance attribute
class BlackBox:
def __init__(self):
self.C = rand.randint(100)
def check(self, guess):
return (guess - self.C) / abs(guess - self.C)
Now you can create one or more BlackBox() instances, and each one has its own random number.
Closure variable
def blackbox():
C = rand.random()
def check(guess):
return (guess - C) / abs(guess - C)
return check
Now, you can create one or more check functions, and each one has its own random number. (This is dual to the instance variable—that is, it has the same capabilities—but usually one or the other is more readable.)
Global variable
def makeblackbox():
global C
C = random.randint(100)
def check(guess):
return (guess - C) / abs(guess - C)
This way, there's only a single blackbox for the entire program. That's usually not as good a design, which is one of the reasons that "globals are bad". Plus, it's polluting the global namespace with a C variable that means nothing to anyone but the check function, which is another one of the reasons that "globals are bad".
Function attribute
def makeblackbox():
check.C = random.randint(100)
def check():
return (guess - check.C) / abs(guess - check.C)
This is equivalent to a global in that you can only ever have one black box, but at least the variable is hidden away on the check function instead of polluting the global namespace.
Class attribute
class BlackBox:
C = rand.randint(100)
#staticmethod
def check(guess):
return (guess - BlackBox.C) / abs(guess - BlackBox.C)
This is again equivalent to a global variable without polluting the global namespace. But it has a downside over the function attribute—you're creating a class that has no useful instances is often misleading.
Class attribute 2
class BlackBox:
C = rand.randint(100)
#classmethod
def check(cls, guess):
return (guess - cls.C) / abs(guess - cls.C)
This is different from the last three in that you can create new blackboxes by creating subclasses of BlackBox. But this is very rarely what you actually want to do. If you want multiple persistent values, you probably want instances.

Since you are asking in the comments.
This is probably not recommended way but it's easy and works so I'll add it here.
You can use global variable to achieve your goal.
import random
persistant_var = 0
def your_func():
global persistant_var
if persistant_var:
print('variable already set {}'.format(persistant_var))
else:
print('setting variable')
persistant_var = random.randint(1,10)
your_func()
your_func()
Output:
setting variable
variable already set 7
Hope this is clear.