Python class can't find member

Question

I tried to put some basic preprocessing operations of a pandas dataframe into a seperate class:

import pandas as pd
import numpy as np
from numba import jit
class MyClass:
 def _init_(self):
 pass
 @jit
 def preprocess_dataframe(self, path):
 self.df = pd.read_csv(path, index_col=False, delimiter=' ' , names=['Time', 'Downloads', 'ServerID', 'Server', 'Date'], usecols=['Time', 'Downloads', 'Server', 'Date'])
 print(self.df.head(5))
 self.df['Date'] = self.df['Date'].astype(str)
 self.df['Timestamp'] = pd.to_datetime(self.df['Time'] +' '+ self.df['Date'], format='%H:%M:%S %Y%m%d')
 self.df[['Server_alone', 'Instance']] = self.df['Server'].str.split('-' ,expand=True)
 self.df.drop(columns=['Time'], inplace=True)
 self.df['Date'] = pd.to_datetime(self.df['Date'], format='%Y-%m-%d')
 self.df.set_index(self.df['Date'])
 return self.df

When I call this function in my main script (see below) I receive the error:

AttributeError: module 'MyClass' has no attribute 'preprocess_dataframe'

This is the relevant part of my main script:

import MyClass as mc
path = 'Data.txt'
df = mc.preprocess_dataframe(path)
>>>AttributeError: module 'MyClass' has no attribute 'preprocess_dataframe'

I looked up several other questions including this. However, nothing solved my issue despite I think that the fix is quite easy. Thank you for your help!

• Sam Mason: I think you should be doing obj = mc.MyClass()
• Sparky05: you need an instance of the class to call its method or make the method static
• Mike_H: @Sparky05 How do I make it static?
• Sparky05: Add an @staticmethod see here stackoverflow.com/questions/735975/static-methods-in-python
• Mike_H: I receive the error 'module' object is not callable @SamMason

Answer 1

You haven't created an instance of the MyClass. You could rectify it by:

df = mc().preprocess_dataframe(path)

Also change the import statement as well to : from filename import MyClass as mc

You could also make preprocess_dataframe a staticmethod as mentioned in comments.

• Mike_H: I receive the error 'module' object is not callable
• GGJON: I expected this error. You will have change the import statement as well to : ` from MyClassfilename import MyClass as mc`
• Mike_H: I think we are close, now I get this error while calling the function TypeError: preprocess_dataframe() missing 1 required positional argument: 'path'. It must be connected to the method defintion. Do I have to provide something for self as well?
• GGJON: Did you add mc().preprocess_dataframe(path) as suggested in the answer? Emphasis on mc()
• Mike_H: Yes I included it

Answer 2

You should make the method static

import pandas as pd
import numpy as np
from numba import jit
class MyClass:
 @jit
 @staticmethod
 def preprocess_dataframe(path):
 df = pd.read_csv(path, index_col=False, delimiter=' ' , names=['Time', 'Downloads', 'ServerID', 'Server', 'Date'], usecols=['Time', 'Downloads', 'Server', 'Date'])
 print(self.df.head(5))
 df['Date'] = df['Date'].astype(str)
 df['Timestamp'] = pd.to_datetime(df['Time'] +' '+ df['Date'], format='%H:%M:%S %Y%m%d')
 df[['Server_alone', 'Instance']] = df['Server'].str.split('-' ,expand=True)
 df.drop(columns=['Time'], inplace=True)
 sdf['Date'] = pd.to_datetime(df['Date'], format='%Y-%m-%d')
 df.set_index(df['Date'])
 return df

and call it the following way

from filename import MyClass
path = 'Data.txt'
df = MyClass.preprocess_dataframe(path)

• Mike_H: That answer might be pretty close. However, I receive this error now: TypeError: preprocess_dataframe() missing 1 required positional argument: 'path' Maybe it has to do something with having (self, path as arguments before?
• Sparky05: You must remove the self argument. I have changed the method, too. (Removing all references to self)
• Mike_H: It perfectly works now. I named MyClass differently in my code. It was kind of an example code right here. Failed to replace everything properly on copy paste. Thanks a lot!
• Sparky05: If you don't want to bundle multiple function inside this class, you don't need the class and could simply define and call the function
• Mike_H: As I have multiple other functions defined in my class, I will keep it in this structure. But thank you for this input, which might ge relevant for other users having the same question. :)