Python Modules
What is a Module?
Consider a module to be the same as a code library.
A file containing a set of functions you want to include in your application.
Create a Module
To create a module just save the code you want in a file with the file extension .py:
Example
Save this code in a file named mymodule.py
def greeting(name): print("Hello, " + name) |
Use a Module
Now we can use the module we just created, by using the import statement:
Example
Import the module named mymodule, and call the greeting function:
import mymodule mymodule.greeting("Jonathan") |
Note: When using a function from a module, use the syntax: module_name.function_name. |
Variables in Module
The module can contain functions, as already described, but also variables of all types (arrays, dictionaries, objects etc):
Example
Save this code in the file mymodule.py
person1 = { "name": "John", "age": 36, "country": "Norway" } |
Example
Import the module named mymodule, and access the person1 dictionary:
import mymodule a = mymodule.person1["age"] print(a) |
Naming a Module
You can name the module file whatever you like, but it must have the file extension .py
Re-naming a Module
You can create an alias when you import a module, by using the as keyword:
Example
Create an alias for mymodule called mx:
import mymodule as mx a = mx.person1["age"] print(a) |
Built-in Modules
There are several built-in modules in Python, which you can import whenever you like.
Example
Import and use the platform module:
import platform x = platform.system() print(x) |
Using the dir() Function
There is a built-in function to list all the function names (or variable names) in a module. The dir() function:
Example
List all the defined names belonging to the platform module:
import platform x = dir(platform) print(x) |
Note: The dir() function can be used on all modules, also the ones you create yourself. |
Import From Module
You can choose to import only parts from a module, by using the from keyword.
Example
The module named mymodule has one function and one dictionary:
def greeting(name): print("Hello, " + name) person1 = { "name": "John", "age": 36, "country": "Norway" } |
Example
Import only the person1 dictionary from the module:
from mymodule import person1 print (person1["age"]) |
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