Python Modules

A 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.

Example:

# A simple module, calc.py

def add(x, y):
    return (x+y)

def subtract(x, y):
    return (x-y)

 
The import statement
We can use any Python source file as a module by executing an import statement in some other Python source file.
When 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 :

# importing  module calc.py
import calc

print add(10, 2)

Output:

12

 

The from import Statement

Python’s from statement lets you import specific attributes from a module. The from .. import .. has the following syntax :

# importing sqrt() and factorial from the 
# module math
from 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

 

The dir() function
The dir() built-in function returns a sorted list of strings containing the names defined by a module. The list contains the names of all the modules, variables and functions that are defined in a module.

#  Import built-in module  random
import  random
print  dir(math)

Output:

['BPF', 'LOG4', 'NV_MAGICCONST', 'RECIP_BPF', 'Random', 
'SG_MAGICCONST', 'SystemRandom', 'TWOPI', 'WichmannHill', 
'_BuiltinMethodType', '_MethodType', '__all__', 
'__builtins__', '__doc__', '__file__', '__name__', 
'__package__', '_acos', '_ceil', '_cos', '_e', '_exp', 
'_hashlib', '_hexlify', '_inst', '_log', '_pi', '_random',
'_sin', '_sqrt', '_test', '_test_generator', '_urandom',
'_warn', 'betavariate', 'choice', 'division', 
'expovariate', 'gammavariate', 'gauss', 'getrandbits',
'getstate', 'jumpahead', 'lognormvariate', 'normalvariate',
'paretovariate', 'randint', 'random', 'randrange', 
'sample', 'seed', 'setstate', 'shuffle', 'triangular', 
'uniform', 'vonmisesvariate', 'weibullvariate']

 

Code Snippet illustrating python built-in modules:

# importing built-in module math
import math

# using square root(sqrt) function contained 
# in math module
print math.sqrt(25) 

# using pi function contained in math module
print math.pi 

# 2 radians = 114.59 degreees
print math.degrees(2) 

# 60 degrees = 1.04 radians
print math.radians(60) 

# Sine of 2 radians
print math.sin(2) 

# Cosine of 0.5 radians
print math.cos(0.5) 

# Tangent of 0.23 radians
print math.tan(0.23)

# 1 * 2 * 3 * 4 = 24
print math.factorial(4) 


# importing built in module random
import random

# printing random integer between 0 and 5
print random.randint(0, 5) 

# print random floating point number between 0 and 1
print random.random() 

# random number between 0 and 100
print 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 list
print random.choice(List)


# importing built in module datetime
import datetime
from datetime import date
import time

# Returns the number of seconds since the
# Unix Epoch, January 1st 1970
print time.time() 

# Converts a number of seconds to a date object
print 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
1970-01-06

This article is contributed by Gaurav Shrestha. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.