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Global And Local Variables Modules Importing Module


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")

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)

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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