Passing a function argument through another function in Python

Question

When giving a string-parameter to a function which i want to use as an argument inside the function for another function:

def function(classifier, classifier_argument, list_of_parameters):
    classifier(classifier_argument=list_of_parameter[0])

classifier = someClassifier()
classifier_argument = 'someArgument'
list_of_parameters = [0,1,2,3,4,5]

func(classifier,classifier_argument,list_of_parameters)

It gives me this error:

TypeError: 'classifier_argument' is an invalid keyword argument for this function

So I know I can't pass it as a simple string, so my question is:

How can i pass it?

Sijan Bhandari · Accepted Answer · 2018-07-05 10:39:06Z

2

In my guess, you are trying to achieve your classifier creation class to be initiated with different attributes as follows ? You can create class attributes dynamically on you __init__ method and use **kwargs to send the required data.

class someClassifier(object):

    def __init__(self, **kwargs):
        for k, v in kwargs.items():
            setattr(self, k, v)
            print('setting classifier attribute', k, v)


def function(classifier, **kwargs):
    classifier(**kwargs)


classifier = someClassifier

list_of_parameters = [0, 1, 2, 3, 4, 5]
classifier_argument = {
    'someArgument': list_of_parameters
}


function(classifier, **classifier_argument)

answered Jul 5, 2018 at 10:39

Sijan Bhandari

3,0713 gold badges25 silver badges38 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Martin Bosch Over a year ago

actually its a class from sklearn, so you suggest to manipulate the init in this library or write this someClassifier() class by myself somehow? Actually its my goal to go directly in the classifier, because it should be dynamic for other classifiers as well.

Sijan Bhandari Over a year ago

If you using sklearn then it will not be a problem to instantiate any of the classifiers. But, you need to make sure the parameters match in your call. So, the above approach will work. Just you need to send right parameters to your function. Like I did above using dict.

John Go-Soco · Accepted Answer · 2018-07-05 10:50:01Z

0

def function(classifier, classifier_argument, list_of_parameters):
    args = {classifier_argument:list_of_parameters}
    classifier(**args)

classifier = someClassifier # Note - you need to reference the function itself, not call it!
classifier_argument = 'someArgument'
list_of_parameters = [0,1,2,3,4,5]

function(classifier,classifier_argument,list_of_parameters)

A couple of points here: you have to unpack the arguments list, and you need to pass in the classsifier function without calling it.

answered Jul 5, 2018 at 10:50

John Go-Soco

9541 gold badge10 silver badges22 bronze badges

4 Comments

Martin Bosch Over a year ago

This produces me another error: TypeError: 'someClassifier' object is not callable. Note: It doesn't make a difference when i reference my classifier before.

John Go-Soco Over a year ago

Can you point out what your error is? I manage to run this code fine (though obviously I've defined my own someClassifier function, which has an argument called "someArgument".

John Go-Soco Over a year ago

I might be misunderstanding your intent. Perhaps you should just do classifier = someClassifier() after all?

Martin Bosch Over a year ago

Ok i got the problem resolved, it was the reference you pointed out. I should edit it. My problem was that i referenced the function i wanted to use before function call. It worked when I referenced it. Note: I used this classifier for another function inside the function, so the solution from John Go-Soco perfectly fits my stated problem (just not the one I was actually working on). Thanks a lot.

atline · Accepted Answer · 2018-07-05 09:28:25Z

0

You could use ** when call function:

def function(classifier, classifier_argument, list_of_parameters):
    paras = {classifier_argument: list_of_parameter[0]}
    classifier(**paras)

classifier = someClassifier()
classifier_argument = 'someArgument'
list_of_parameters = [0,1,2,3,4,5]

func(classifier,classifier_argument,list_of_parameters)

A more simple workable example for your quick test:

def fun1(b):
    print(b)

def fun(a):
    paras = {a: 2}
    fun1(**paras)

fun('b')

answered Jul 5, 2018 at 9:28

atline

32.1k19 gold badges102 silver badges134 bronze badges

Collectives™ on Stack Overflow

Passing a function argument through another function in Python

3 Answers 3

2 Comments

4 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related