Passing Function as parameter in python

Question

I am trying to make a function to calculate rolling mean or sum :

def rolling_lag_creator(dataset,i,func):  
    dataset['Bid']=dataset.loc[:,'Bid'].rolling(window=i).func()
    return dataset

but this function is throwing error when i am calling this:

rolling_lag_creator(Hypothesis_ADS,5,mean)

Error:

NameError: name 'mean' is not defined

while below code works fine:

dataset['Bid']=dataset.loc[:,'Bid'].rolling(window=5).mean()

Can anyone help me how to call such methods as parameters, thank you.

The error message is telling you “name ‘mean’ is not defined’. You need to define the function mean. Or refer to an existing function mean() — DisappointedByUnaccountableMod
– DisappointedByUnaccountableMod, Commented May 25, 2020 at 19:39
Rolling function return is rolling object and is not working — Manish Kumar Singh
– Manish Kumar Singh, Commented May 25, 2020 at 19:53

wjandrea · Accepted Answer · 2020-05-25 19:53:43Z

1

mean is a method, not a function per se. And anyway, attribute access doesn't work like that, but you can use getattr, something like this:

def rolling_lag_creator(dataset, i, method_name):
    method = getattr(dataset.loc[:,'Bid'].rolling(window=i), method_name)
    dataset['Bid'] = method()
    return dataset

rolling_lag_creator(Hypothesis_ADS, 5, 'mean')

answered May 25, 2020 at 19:53

wjandrea

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1 Comment

Manish Kumar Singh Over a year ago

Waao , thanks your answer works flawlessly , this is what i needed thank you so much

Roy2012 · Accepted Answer · 2020-05-25 19:39:53Z

0

I guess you need to:

import numpy as np

and then replace mean with np.mean

answered May 25, 2020 at 19:39

Roy2012

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