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Python import Statement

Python import statement enables the user to import particular modules in the corresponding program.

It resembles the #include header_file in C/C++.

As soon as the interpreter encounters the import statement in a particular code, it searches for the same in the local scope and imports the module, if present in the search path.

It searches for a particular module in its built-in modules section at first. If it’s not found, it searches those modules in its current directory.

A module is loaded only once in a particular program, without being affected by the number of times the module is imported.

Syntax:

import module_name

Example:

import collections

1. Importing class/functions from a module

We can import classes/functions from a module using the syntax:

from {module} import {class/function}

Example:

from collections import OrderedDict
from os import path
from math import pi
print(pi)

Output:

3.141592653589793

2. The import * Statement

All the methods and constants of a particular module can be imported using import * operator.

from math import *
print(pi)
print(floor(3.15))

Output:

3.141592653589793
3

3. Python’s import as Statement

The import as statement helps the user provide an alias name to the original module name.

# python import as
import math as M

print(M.pi)
print(M.floor(3.18))

Output:

3.141592653589793
3

4. Importing user-defined modules

We can import the functions of one program into another using its name.

Initially, we need to create a python code.

test.py

def sub(a, b):
    return int(a) - int(b)

def lower_case(str1):
    return str(str1).lower()

Then create another python script, wherein we need to import the above create test.py script.

test2.py

import test

print(test.sub(5,4))
print(test.lower_case('SafA'))

Output:

1
safa

5. Importing from another directory

The importlib library is used to import a script from another directory.

Initially, we need to create a python script and define functions in it.

test1.py

def sub(a, b):
    return int(a) - int(b)

def lower_case(str1):
    return str(str1).lower()

Then, we will create another python script and save it into another directory and then import the functionalities from test1.py (which resides into another directory).

design.py

import importlib, importlib.util

def module_directory(name_module, path):
    P = importlib.util.spec_from_file_location(name_module, path)
    import_module = importlib.util.module_from_spec(P)
    P.loader.exec_module(import_module)
    return import_module

result = module_directory("result", "../inspect_module/test1.py")

print(result.sub(3,2))
print(result.lower_case('SaFa'))

Output:

1
safa

Another alternative way is to add the module directory to the sys.path list.


6. Importing class from another file

tests.py

class Employee:
    designation = ""

    def __init__(self, result):
        self.designation = result

    def show_designation(self):
        print(self.designation)


class Details(Employee):
    id = 0

    def __init__(self, ID, name):
        Employee.__init__(self, name)
        self.id = name

    def get_Id(self):
        return self.id

design.py

import importlib, importlib.util

def module_directory(name_module, path):
    P = importlib.util.spec_from_file_location(name_module, path)
    import_module = importlib.util.module_from_spec(P)
    P.loader.exec_module(import_module)
    return import_module

result = module_directory("result", "../Hello/tests.py")

a = result.Employee('Project Manager')
a.show_designation()

x = result.Details(4001,'Safa')
x.show_designation()
print(x.get_Id())

Output:

Project Manager
Safa
Safa

Conclusion

Thus, in this article, we have understood the functionalities offered by the import statement.


References