CODEWITHSUNDEEP
python
Ophilia
Ophilia

Reputation: 717

create multiple objects of a class with different arguments

I know how to create multiple objects of the same class using a loop, similar to this How to create multiple class objects with a loop in python? However, what I want is different because each object has to be initialised with different arguments my program now reads all the information (the arguments) from a file and store them in a python dictionary, like this:

objects={'obj1':['object1','Tom',10],'obj2':['object2','John',13]}

and because the number of the objects which are needed depend on the information found on the file .. I want to know if there's a way to automatically create (maybe by using a loop !) multiple class objects and initialised them with their different arguments .. Instead of declare them as follows: 

obj1 = MyClass('object1','Tom',10)
obj2 = MyClass('object2','John',13)

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etc

Upvotes: 2

Views: 3555

Answers (3)

Jan Vlcinsky
Jan Vlcinsky

Reputation: 44092

>>> objects={'obj1':['object1','Tom',10],'obj2':['object2','John',13]}
>>> instances = []
>>> for name, args in objects.items():
        inst = MyClass(*args)
        instances.append(inst)

Or directly:

>>> [MyClass(*args) for name, args in objects.items()]
[<MyClass: object1, Tom, 10>, <MyClass: object2, John, 13>]

or even simpler, ignoring names:

>>> [MyClass(*args) for args in objects.values()]
[<MyClass: object1, Tom, 10>, <MyClass: object2, John, 13>]

or returning a dictionary (works in Python 2.7+)

>>> {name: MyClass(*args) for name, args in objects.items()}
{'obj1': <MyClass: object1, Tom, 10>, 'obj2': <MyClass: object2, John, 13>}

This would even work if you have dynamic number of arguments for creating your instances (assuming your class constructor can handle this variable number - using defaults)

Using itertools.starmap

>>> from itertools import starmap
>>> list(starmap(MyClass, objects.values())
[<MyClass: object1, Tom, 10>, <MyClass: object2, John, 13>]

Upvotes: 4

Vor
Vor

Reputation: 35109

objects={'obj1':['object1','Tom',10],'obj2':['object2','John',13]}
class MyClass():
  def __init__(self, var1, var2, var3, *args):
    self.var1 = var1
    self.var2 = var2
    self.var3 = var3

for i in objects.keys():
  my_class = MyClass(*objects[i])
  print my_class.__dict__

{'var1': 'object1', 'var3': 10, 'var2': 'Tom'}
{'var1': 'object2', 'var3': 13, 'var2': 'John'}

Upvotes: 2

Luigi
Luigi

Reputation: 4129

One thing you could do is create a list containing all of your new MyClass objects, like so:

class_objects = []
for o in objects.values():
    class_objects.append(MyClass(o[0], o[1], o[2]))

This makes a list called class_objects that contains all of your MyClass objects from the file.

Upvotes: 1

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