Best way to call Python class methods automatically upon instantiation

Question

I have a machine learning algorithm which involves a series of steps, such as cleaning data, preparing training data etc. Each step is stored in a separate method of a python class. I’m wondering what the best practice way to structure my class is so that the steps are automatically executed upon class instantiation.

Here’s what I’ve done (the code is illustrative, but this approach works on the real algorithm). It feels a little clunky. Is there a more elegant way?

 class Kaggle():
    """
    An algorithm
    """

    def __init__( self ):
        self.bar = 1

    def step_one( self, some_text_data ):
        self.bar = 1 ** 2
        # Do some data cleaning
        # return processed data

    def step_two( self ):
        foo = step_one(baz)
        # do some more processing

    def step_three( self ):
        bar = step_two()
        # output results

    def run( self ):
        self.step_one()
        self.step_two()
        self.step_three()

if __name__ == "__main__":
    kaggle = Kaggle()
    kaggle.run()

Asked By: cs_stackX

||

Source

Answer 1

Put all the calls in your __init__ method. Is this not what you wanted to achieve? You could add a flag with a default value, that allows you to not run the tests if you want.

def __init__( self, runtests=True ):
    self.bar = 1
    if runtests:
        self.step_one()
        self.step_two()
        self.step_three()

Answered By: Paul Rooney

Answer 2

If your goal is for the object to be "automatically executed upon class instantiation", just put self.run() in the init:

def __init__(self):
    self.bar = 1
    self.run()

As an aside, one should try to keep the __init__ method lightweight and just use it to instantiate the object. Although "clunky", your original Kaggle class is how I would design it (i.e. instantiate the object and then have a separate run method to run your pipeline). I might rename run to run_pipeline for better readability, but everything else looks good to me.

Answered By: Alexander

Answer 3

Old thread, but was working with dataclasses and found this to work as well

from dataclasses import dataclass

@dataclass
class MyClass:
    var1: str
    var2: str

    def __post_init__(self):
        self.func1()
        self.func2()

    def func1(self):
        print(self.var1)

    def func2(self):
        print(self.var2)

a = MyClass('Hello', 'World!')
Hello
World!

Answered By: solly989

Best way to call Python class methods automatically upon instantiation

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