I want to know how can I pass argument from a class to two different functions inside. I import this file, called test.py and I have to pass two arguments (name_t,name_s) from another file suppose caledl passing.py. So I want to do is like this (I know it's wrong but it is to explain my point):
(passing.py)
from test import M
name_t = 'tomas'
name_s = 'santino'
M(name_t,name_s)
(test.py)
class M():
def values():
tapi = name_t
def loop():
symbol = name_s
Use an __init__() method to get the parameters and set attributes.
class M():
def __init__(self, name_t, name_s):
self.tapi = name_t
self.symbol = name_s
def values(self):
print(self.tapi)
def loop(self):
print(self.symbol)
name_t = 'tomas'
name_s = 'santino'
m = M(name_t, name_s)
m.values()
m.loop()
Related
Say I have 2 different implementations of a class
class ParentA:
def initialize(self):
pass
def some_event(self):
pass
def order(self, value):
# handle order in some way for Parent A
class ParentB:
def initialize(self):
pass
def some_event(self):
pass
def order(self, value):
# handle order in another for Parent B
How can I dynamically let some 3rd class inherit from either ParentA or ParentB based on something like this?
class MyCode:
def initialize(self):
self.initial_value = 1
def some_event(self):
# handle event
order(self.initial_value)
# let MyCode inherit from ParentA and run
run(my_code, ParentA)
Simply store the class-object in a variable (in the example below, it is named base), and use the variable in the base-class-spec of your class statement.
def get_my_code(base):
class MyCode(base):
def initialize(self):
...
return MyCode
my_code = get_my_code(ParentA)
Also, you can use type builtin. As callable, it takes arguments: name, bases, dct (in its simplest form).
def initialize(self):
self.initial_value = 1
def some_event(self):
# handle event
order(self.initial_value)
subclass_body_dict = {
"initialize": initialize,
"some_event": some_event
}
base_class = ParentA # or ParentB, as you wish
MyCode = type("MyCode", (base_class, ), subclass_body_dict)
This is more explicit than snx2 solution, but still - I like his way better.
PS. of course, you dont have to store base_class, nor subclass_body_dict, you can build those values in type() call like:
MyCode = type("MyCode", (ParentA, ), {
"initialize": initialize,
"some_event": some_event
})
Just as a quick copy-and-paste-ready snippet, I've added the comments from shx2's answer to create this (memoized with a created_classes dict attribute, so that the classes created by successive identical calls with the same class will give identical classes):
class ParentA:
val = "ParentA"
class ParentB:
val = "ParentB"
class DynamicClassCreator():
def __init__(self):
self.created_classes = {}
def __call__(self, *bases):
rep = ",".join([i.__name__ for i in bases])
if rep in self.created_classes:
return self.created_classes[rep]
class MyCode(*bases):
pass
self.created_classes[rep] = MyCode
return MyCode
creator = DynamicClassCreator()
instance1 = creator(ParentA, ParentB)()
print(instance1.val) #prints "ParentA"
instance2 = creator(ParentB, ParentA)()
print(instance2.val) #prints "ParentB"
If you wanted to get fancy you could even make DynamicClassCreator a Singleton: https://stackoverflow.com/a/7346105/5122790
As an alternative to Chris's answer implementing the memoisation suggestion for shx2's answer, I'd prefer to use a memoize decorator (the end result is still a class but it's clearer to me that the function is the interface), and also use setdefault to simplify adding to the memo dict, and do not convert the names to string but use the tuple bases itself as the key, simplifying the code to:
class Memoize:
def __init__(self, f):
self.f = f
self.memo = {}
def __call__(self, *args):
return self.memo.setdefault(args, self.f(*args))
class ParentA:
def initialize(self):
pass
class ParentB:
def initialize(self):
pass
#Memoize
def get_my_code(base):
class MyCode(base):
def initialize(self):
pass
return MyCode
a1 = get_my_code(ParentA)
a2 = get_my_code(ParentA)
b1 = get_my_code(ParentB)
print(a1 is a2) # True
print(a1 is b1) # False
(Not a good example as the code provided doesn't actually do anything other than overwrite the parent class's initialize method...)
I am making a few sub-classes that needs to implement a run method. They all follow a pattern:
from mylib import transformation_function_1
from mylib import transformation_function_2
def SubClass1(ParentClass):
def run(self):
subclass_data = transformation_function_1(self.parent_data)
# Some other fixed logic.
def SubClass2(ParentClass):
def run(self):
subclass_data = transformation_function_2(self.parent_data)
# Some other fixed logic.
Is there anyway I can pull out this logic in a intermediate class? Something like this?
from mylib import transformation_function_1
from mylib import transformation_function_2
def TransformationBase(ParentClass):
#abstractclassmethod
def transformation_function():
raise NotImplementedError
def run(self):
subclass_data = transformation_function(self.parent_data)
# Some other fixed logic.
def SubClass1(TransformationBase):
transformation_function = transformation_function_1
def SubClass2(TransformationBase):
transformation_function = transformation_function_2
Thanks!
The special function staticmethod allows to declare local methods as being static. Assuming that you wanted to declare classes and that you want that subclasses make use of external free functions, you could do:
>>> class TransformationBase:
def transformation_function():
raise NotImplementedError
def run(self):
subclass_data = self.transformation_function(self.parent_data)
# Some other fixed logic.
>>> def transformation_function_1(data):
print('F1', data)
>>> def transformation_function_2(data):
print('F2', data)
return 2
>>> class SubClass1(TransformationBase):
transformation_function = staticmethod(transformation_function_1)
parent_data = "P1"
>>> c1 = SubClass1()
>>> c1.run()
F1 P1
>>>
You can do something like:
class SubClass(TransformationBase):
def transformation_function(*args, **kwargs):
return transformation_function1(*args, **kwargs)
I just started learning Python and I don't quite understand where the problem in this code is. I have a base class Proband with two methods and I want to create a subclass Gesunder and I want to override the attributes idn,artefakte.
import scipy.io
class Proband:
def __init__(self,idn,artefakte):
self.__idn = idn
self.artefakte = artefakte
def getData(self):
path = 'C:\matlab\EKGnurbild_von Proband'+ str(self.idn)
return scipy.io.loadmat(path)
def __eq__(self,neueProband):
return self.idn == neueProband.idn and self.artefakte == neueProband.artefakte
class Gesunder(Proband):
def __init__(self,idn,artefakte,sportler):
super().__init__(self,idn,artefakte)
self.__sportler = sportler
hans = Gesunder(2,3,3)
You have 2 problems in your code. In python 2:
super() takes 2 arguments: the class name, and the instance
in order to use super(), the base class must inherit from object
So your code becomes:
import scipy.io
class Proband(object):
def __init__(self,idn,artefakte):
self.__idn = idn
self.artefakte = artefakte
def getData(self):
path = 'C:\matlab\EKGnurbild_von Proband'+ str(self.idn)
return scipy.io.loadmat(path)
def __eq__(self,neueProband):
return self.idn == neueProband.idn and self.artefakte == neueProband.artefakte
class Gesunder(Proband):
def __init__(self,idn,artefakte,sportler):
super(Gesunder, self).__init__(idn,artefakte)
self.__sportler = sportler
hans = Gesunder(2,3,3)
Note the the call to super(Gesunder, self).__init__ does not have self as the first argument.
In Python 2, super() on its own is invalid. Instead, you must use super(ClassName, self).
super(Gesunder, self).__init__(self, idn, artefakte)
The super() call should be modified to :
super(Gesunder, self).__init__(self, idn, artefakte)
I've been trying to create a genetic algorithm in python but i either get:
<bound method Environment.bestsol of <__main__.Environment instance
at 0x10a5d4ab8>>
or it doesn't print. I've tried to rearrange the functions, and call the function directly, but it still does not output anything. I seem to be having trouble with something relating to the function bestsol().
import random
import sys
from operator import attrgetter
input = 1
target = 5.5
class Individual:
def __init__(self, constant):
self.fitness = getfitness()
self.constant = constant
def getconstant():
return self.constant
def getresult():
return self.constant * input
def getfitness():
return 10 - abs(target - self.getresult())
def mutate():
if(random.random() > .05):
self.constant + random.random()
def offspring(partner):
return Individual(((self.getconstant() + partner.getconstant())/2))
class Generation(list):
def __init__(self, gensize, fitsize, startinglist=[]):
self.extend(startinglist)
self.bredoff = []
self.gensize = gensize
self.fitsize = fitsize
self.make()
def make():
self = [Individual(random.randint(-10,10)) for x in xrange((self.gensize-len(self)))]
def getfittest():
return heapq.nlargest(self.fitsize,self,key=attrgetter('fitness'))
def getbredoffspring():
for i in self.getfittest():
bredoff.append(i.offspring(self.getfittest[random.randint(0,len(self.getfittest()))]))
return bredoff
class Environment():
def __init__(self, maxgens):
self.l = []
self.b = []
self.maxgens = maxgens
def create():
l = Generation(100,20)
for i in maxgens:
b = l.getbredoffspring()
l = Generation(100,20,b)
def bestsol():
print("e")
print max(l,key=attrgetter('fitness')).fitness()
def main():
sol = Environment(2)
print sol.bestsol
if __name__ == '__main__':
main()
With me being new to python i can't understand even after searching the internet as best i could. Any help will be appreciated.
bestsol is a class method, so when you call it you should use brackets: sol.bestsol() (otherwise, you're print the method object: <bound method Environment.bestsol ...).
Second, when you define a class-method you should declare self as an argument:
def bestsol(self): # <-- here
print("e")
print max(l,key=attrgetter('fitness')).fitness()
Third, when you declare a class that doesn't extend any other class - you should either declare that it inherits from object (old way):
class Environment(object):
or, no brackets at all (new way)
class Environment:
Forth, when you create a class member, say l (you really should use better names btw), whenever you want to use it you should use the self annotation: self.l. If you'll use l it will create a local variable inside the method - and that's probably not what you intended.
There are other problems with the code but I'll let you struggle with it a bit so you can learn :)
I have a model where I want to use a class method to set the default of for a property:
class Organisation(db.Model):
name=db.StringProperty()
code=db.StringProperty(default=generate_code())
#classmethod
def generate_code(cls):
import random
codeChars='ABCDEF0123456789'
while True: # Make sure code is unique
code=random.choice(codeChars)+random.choice(codeChars)+\
random.choice(codeChars)+random.choice(codeChars)
if not cls.all().filter('code = ',code).get(keys_only=True):
return code
But I get a NameError:
NameError: name 'generate_code' is not defined
How can I access generate_code()?
As I said in a comment, I would use a classmethod to act as a factory and always create you entity through there. It keeps things simpler and no nasty hooks to get the behaviour you want.
Here is a quick example.
class Organisation(db.Model):
name=db.StringProperty()
code=db.StringProperty()
#classmethod
def generate_code(cls):
import random
codeChars='ABCDEF0123456789'
while True: # Make sure code is unique
code=random.choice(codeChars)+random.choice(codeChars)+\
random.choice(codeChars)+random.choice(codeChars)
if not cls.all().filter('code = ',code).get(keys_only=True):
return code
#classmethod
def make_organisation(cls,*args,**kwargs):
new_org = cls(*args,**kwargs)
new_org.code = cls.generate_code()
return new_org
import random
class Test(object):
def __new__(cls):
cls.my_attr = cls.get_code()
return super(Test, cls).__new__(cls)
#classmethod
def get_code(cls):
return random.randrange(10)
t = Test()
print t.my_attr
You need specify the class name: Organisation.generate_code()