Python Modules
In this article, we will cover all about Python modules, such as How to create our own simple module, Import Python modules, From statements in Python, how we can use the alias to rename the module, etc.
What is Python Module
A Python module is a file containing Python definitions and statements. A module can define functions, classes, and variables. A module can also include runnable code. Grouping related code into a module makes the code easier to understand and use. It also makes the code logically organized.
Create a simple Python module
Let’s create a simple calc.py in which we define two functions, one add and another subtract.
Python3
# A simple module, calc.pydef add(x, y): return (x+y)def subtract(x, y): return (x-y) |
Import Module in Python
We can import the functions, and classes defined in a module to another module using the import statement in some other Python source file.
When the interpreter encounters an import statement, it imports the module if the module is present in the search path. A search path is a list of directories that the interpreter searches for importing a module. For example, to import the module calc.py, we need to put the following command at the top of the script.
Syntax of Python Import
import module
Note: This does not import the functions or classes directly instead imports the module only. To access the functions inside the module the dot(.) operator is used.
Importing modules in Python
Now, we are importing the calc that we created earlier to perform add operation.
Python3
# importing module calc.pyimport calcprint(calc.add(10, 2)) |
Output:
12
The from-import Statement in Python
Python’s from statement lets you import specific attributes from a module without importing the module as a whole.
Importing specific attributes from the module
Here, we are importing specific sqrt and factorial attributes from the math module.
Python3
# importing sqrt() and factorial from the# module mathfrom math import sqrt, factorial# if we simply do "import math", then# math.sqrt(16) and math.factorial()# are required.print(sqrt(16))print(factorial(6)) |
Output:
4.0 720
Import all Names
The * symbol used with the from import statement is used to import all the names from a module to a current namespace.
Syntax:
from module_name import *
From import * Statement
The use of * has its advantages and disadvantages. If you know exactly what you will be needing from the module, it is not recommended to use *, else do so.
Python3
# importing sqrt() and factorial from the# module mathfrom math import *# if we simply do "import math", then# math.sqrt(16) and math.factorial()# are required.print(sqrt(16))print(factorial(6)) |
Output
4.0 720
Locating Python Modules
Whenever a module is imported in Python the interpreter looks for several locations. First, it will check for the built-in module, if not found then it looks for a list of directories defined in the sys.path. Python interpreter searches for the module in the following manner –
- First, it searches for the module in the current directory.
- If the module isn’t found in the current directory, Python then searches each directory in the shell variable PYTHONPATH. The PYTHONPATH is an environment variable, consisting of a list of directories.
- If that also fails python checks the installation-dependent list of directories configured at the time Python is installed.
Directories List for Modules
Here, sys.path is a built-in variable within the sys module. It contains a list of directories that the interpreter will search for the required module.
Python3
# importing sys moduleimport sys# importing sys.pathprint(sys.path) |
Output:
[‘/home/nikhil/Desktop/gfg’, ‘/usr/lib/python38.zip’, ‘/usr/lib/python3.8’, ‘/usr/lib/python3.8/lib-dynload’, ”, ‘/home/nikhil/.local/lib/python3.8/site-packages’, ‘/usr/local/lib/python3.8/dist-packages’, ‘/usr/lib/python3/dist-packages’, ‘/usr/local/lib/python3.8/dist-packages/IPython/extensions’, ‘/home/nikhil/.ipython’]
Renaming the Python module
We can rename the module while importing it using the keyword.
Syntax: Import Module_name as Alias_name
Python3
# importing sqrt() and factorial from the# module mathimport math as mt# if we simply do "import math", then# math.sqrt(16) and math.factorial()# are required.print(mt.sqrt(16))print(mt.factorial(6)) |
4.0 720
Python built-in modules
There are several built-in modules in Python, which you can import whenever you like.
Python3
# importing built-in module mathimport math# using square root(sqrt) function contained# in math moduleprint(math.sqrt(25))# using pi function contained in math moduleprint(math.pi)# 2 radians = 114.59 degreesprint(math.degrees(2)) # 60 degrees = 1.04 radiansprint(math.radians(60)) # Sine of 2 radiansprint(math.sin(2)) # Cosine of 0.5 radiansprint(math.cos(0.5)) # Tangent of 0.23 radiansprint(math.tan(0.23))# 1 * 2 * 3 * 4 = 24print(math.factorial(4)) # importing built in module randomimport random# printing random integer between 0 and 5print(random.randint(0, 5)) # print random floating point number between 0 and 1print(random.random()) # random number between 0 and 100print(random.random() * 100) List = [1, 4, True, 800, "python", 27, "hello"]# using choice function in random module for choosing# a random element from a set such as a listprint(random.choice(List))# importing built in module datetimeimport datetimefrom datetime import dateimport time# Returns the number of seconds since the# Unix Epoch, January 1st 1970print(time.time()) # Converts a number of seconds to a date objectprint(date.fromtimestamp(454554)) |
Output:
5.0 3.14159265359 114.591559026 1.0471975512 0.909297426826 0.87758256189 0.234143362351 24 3 0.401533172951 88.4917616788 True 1461425771.87
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