python – Call a function from another file?

The Question :

587 people think this question is useful

Set_up: I have a .py file for each function I need to use in a program.

In this program, I need to call the function from the external files.

I’ve tried:

from file.py import function(a,b)

But I get the error:

ImportError: No module named ‘file.py’; file is not a package

How do I fix this problem?

The Question Comments :
  • from file import function. No need for file extensions or function parameters
  • You should probably go through the modules section in the Python tutorial.
  • Just make sure if using PyCharms, then it would only recognize an underscore delimited filename.
  • Also if you want to import the function from the file.py, make sure there is no package in your directory with the name file.

The Answer 1

645 people think this answer is useful

There isn’t any need to add file.py while importing. Just write from file import function, and then call the function using function(a, b). The reason why this may not work, is because file is one of Python’s core modules, so I suggest you change the name of your file.

Note that if you’re trying to import functions from a.py to a file called b.py, you will need to make sure that a.py and b.py are in the same directory.

The Answer 2

213 people think this answer is useful

First of all you do not need a .py.

If you have a file a.py and inside you have some functions:

def b():
  # Something
  return 1

def c():
  # Something
  return 2

And you want to import them in z.py you have to write

from a import b, c

The Answer 3

73 people think this answer is useful

You can do this in 2 ways. First is just to import the specific function you want from file.py. To do this use

from file import function

Another way is to import the entire file

import file as fl

Then you can call any function inside file.py using

fl.function(a,b)

The Answer 4

54 people think this answer is useful

If your file is in the different package structure and you want to call it from a different package, then you can call it in that fashion:

Let’s say you have following package structure in your python project:

Python package and file structure

in – com.my.func.DifferentFunction python file you have some function, like:

def add(arg1, arg2):
    return arg1 + arg2

def sub(arg1, arg2) :
    return arg1 - arg2

def mul(arg1, arg2) :
    return arg1 * arg2

And you want to call different functions from Example3.py, then following way you can do it:

Define import statement in Example3.py – file for import all function

from com.my.func.DifferentFunction import *

or define each function name which you want to import

from com.my.func.DifferentFunction import add, sub, mul

Then in Example3.py you can call function for execute:

num1 = 20
num2 = 10

print("\n add : ", add(num1,num2))
print("\n sub : ", sub(num1,num2))
print("\n mul : ", mul(num1,num2))

Output:

 add :  30

 sub :  10

 mul :  200

The Answer 5

43 people think this answer is useful

You can call the function from a different directory as well, in case you cannot or do not want to have the function in the same directory you are working. You can do this in two ways (perhaps there are more alternatives, but these are the ones that have worked for me).

Alternative 1 Temporarily change your working directory

import os

os.chdir("**Put here the directory where you have the file with your function**")

from file import function

os.chdir("**Put here the directory where you were working**")

Alternative 2 Add the directory where you have your function to sys.path

import sys

sys.path.append("**Put here the directory where you have the file with your function**")

from file import function

The Answer 6

25 people think this answer is useful

Came across the same feature but I had to do the below to make it work.

If you are seeing ‘ModuleNotFoundError: No module named’, you probably need the dot(.) in front of the filename as below;

from .file import funtion

The Answer 7

13 people think this answer is useful

First save the file in .py format (for example, my_example.py). And if that file have functions,

def xyz():

        --------

        --------

def abc():

        --------

        --------

In the calling function you just have to type the below lines.

file_name: my_example2.py

============================

import my_example.py


a = my_example.xyz()

b = my_example.abc()

============================

The Answer 8

13 people think this answer is useful

Rename the module to something other than ‘file’.

Then also be sure when you are calling the function that:

1)if you are importing the entire module, you reiterate the module name when calling it:

import module
module.function_name()

or

import pizza
pizza.pizza_function()

2)or if you are importing specific functions, functions with an alias, or all functions using *, you don’t reiterate the module name:

from pizza import pizza_function
pizza_function()

or

from pizza import pizza_function as pf
pf()

or

from pizza import *
pizza_function()

The Answer 9

13 people think this answer is useful

Functions from .py file (can (of course) be in different directory) can be simply imported by writing directories first and then the file name without .py extension:

from directory_name.file_name import function_name

And later be used: function_name()

The Answer 10

9 people think this answer is useful

Inside MathMethod.Py.

def Add(a,b):
   return a+b 

def subtract(a,b):
  return a-b

Inside Main.Py

import MathMethod as MM 
  print(MM.Add(200,1000))

Output:1200

The Answer 11

6 people think this answer is useful

You don’t have to add file.py.

Just keep the file in the same location with the file from where you want to import it. Then just import your functions:

from file import a, b

The Answer 12

5 people think this answer is useful

You should have the file at the same location as that of the Python files you are trying to import. Also ‘from file import function’ is enough.

The Answer 13

5 people think this answer is useful

append a dot(.) in front of a file name if you want to import this file which is in the same directory where you are running your code.

For example, i’m running a file named a.py and i want to import a method named addFun which is written in b.py, and b.py is there in the same directory

from .b import addFun

The Answer 14

2 people think this answer is useful

Suppose the file you want to call is anotherfile.py and the method you want to call is method1, then first import the file and then the method

from anotherfile import method1

if method1 is part of a class, let the class be class1, then

from anotherfile import class1

then create an object of class1, suppose the object name is ob1, then

ob1 = class1()
ob1.method1()

The Answer 15

2 people think this answer is useful

in my case i named my file helper.scrap.py and couldn’t make it work until i changed to helper.py

The Answer 16

2 people think this answer is useful

Any of the above solutions didn’t work for me. I got ModuleNotFoundError: No module named whtever error. So my solution was importing like below

from . import filename # without .py  

inside my first file I have defined function fun like below

# file name is firstFile.py
def fun():
  print('this is fun')

inside the second file lets say I want to call the function fun

from . import firstFile

def secondFunc():
   firstFile.fun() # calling `fun` from the first file

secondFunc() # calling the function `secondFunc` 

The Answer 17

0 people think this answer is useful

in my main script detectiveROB.py file i need call passGen function which generate password hash and that functions is under modules\passwordGen.py

The quickest and easiest solution for me is

Below is my directory structure

enter image description here

So in detectiveROB.py i have import my function with below syntax

from modules.passwordGen import passGen

enter image description here

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