Modules
A module is a file (script), containing definitions and statements. This can be any program that we write/wrote and hope to use that same code without copying and pasting the code into the new script. All we have to do is to import
them.
Example
Consider the code below, this is taken from exercise 12 a (Functions)
.
# file name: area.py
# description:
# A program that calculates and prints the area
# of a triangle taking the base and height as inputs
def calc_area():
base = float(input("Enter base: "))
height = float(input("Enter height: "))
area = 0.5 * base * height
result = f"The area of a triangle of base, {base}"
result += f"and height, {height} is {area}"
print(result)
Import a module
Importing a module is very simple really, all we need is the import
keyword and the module name. The module name is the name of the file/script, without the suffix (extension), .py
import module_name
Import area.py
To import the area.py
, and make use of calc_area
we have to import it.
import area
# think of this `import area` like an object with some
# properties and methods. The dot notation will work here.
# It is for accessing the variables and functions in the
# imported object
area.calc_area()
# refer to this same code in `exercise 12 a (Functions)`
# we called the function similar to how we've done here
# just without the module name and this is because the
# function is in the module
Import objects from a module
Let's assume that there is at least a function in the module and we want to make use of a particular one or all, using the from module import this_functionality ...
annotation.
Add a function that calculates the perimeter of the triangle, calc_peri
, to the area.py
script and rename the module to triangle.py
.
from module_name import object_name
Import a particular object
Our goal here is to import calc_area
and calc_peri
from the triangle
module.
from triangle import calc_area, calc_peri
# call the calculate area function
calc_area()
# with this, we won't have to do, area.calc_area()
# call the calculate perimeter function
calc_peri()
Import all objects
Our goal here is to import all the objects in the module. This can be achieved by using *
to imply all. With this, we have access to all the objects. Remember that import with *
is not a good practice.
from triangle import *
# call the calculate area function
calc_area()
# call the calculate perimeter function
calc_peri()
Note
from module import object
is almost similar to import module
just that with the latter we have to do module.object
to make use of the object.
visit Python doc to read on the builtin modules and packages
Math module
The math module contains some mathematical functions algebra, logarithm, trigonometry, some constants and others.
Let's make use of pi, e, gcd, exp, factorial, pow, sqrt, cos, sin.
pi and e are constants and the rest are functions.
We are going to import a lot of things from the math module thus to keep it structured we shall group them as tuples though it will work fine anyway.
More example
Note
We can do, from module import object as alias
. This may allow the resolution of conflicting names. Say we have Square and Rectangle, with the same function names, we use the alias concept, as
, to resolve it by giving them specific names.
# import employee script
from Employee import Employee as App
print("Employee")
me = App("John Matthew Doe", "Python Developer", 1200.00)
print(f"My name is {me.name} and i am a {me.job}.")
print(f"My salary is {me.salary}.")
print("When i work overtime, My salary for", end=" ")
print(f"the month is {me.return_gross_pay(400)}")
Or
from triangle import calc_area as area, calc_peri as perimeter
# call area
area()
# call perimeter
perimeter()
We could have imported calc_area
and calc_peri
on different lines.
from triangle import calc_area as area
from triangle import calc_peri as perimeter
Practicals

As a practice project, write a script,
mathsmodule.py
that performs mathematical operations such as addition, subtraction, etc. Use a class and create atest.py
script then import it there. Ourmodule
should pass these test.
Assume that the method names will include,add, subtr, mult, div, floor_div, pow, mod
. Add comments and then create a new file,mathsmodule.md
 this can be a.txt
file too. The documentation should have information about the developer, what the module is about, how to use the module, how and what to improve, how the methods work and how to use the methods, some errors we expect to occur, some constants that were used, etc. We hope this is becoming clear. test add
 add(1,2) = 10
 add(1,2) = 1
 add(1,2,3,4) = 10
 test subtr
 subtr(1,2) = 1
 subtr(1,2) = 3
 test mult
 add(1,2) = 2
 add(1,2) = 2
 add(1,2,4) = 8
 test div
 div(1,2) = 0.5
 div(1,2) = 0.5
 div(5, 0) = None
 test floor_div
 floor_div(1,2) = 10
 floor_div(1,2) = 1
 floor_div(1,2,3,4) = 10
 test pow
 pow(1,2) = 1
 pow(2,3) = 8
 pow(2,2) = 0.25
 test mod
 mod(1,2) = 1
 mod(22,7) = 1
For the second version of this program, let a method take 3 args, operator, first_operand, second_operand. Instead of calling any of the methods such as add, just call,
evaluate
with arguments such asevaluate('+', 2, 5)
to return 7. This should work even if the second and third arguments are in a form of strings such asevaluate('+', '2', '5')
.For a third version, instead of the symbols, such as using,
+
, useadd
instead. Thusevaluate(+, 2, 5)
,evaluate('+', '2', '5')
andevaluate('add', 2, 5)
orevaluate('add', '2', '5')
works the same.Write a program that simulates the rolling of a dice. A fair dice has 6 sides numbered from 1 to 6. Take an integer input from the user as the number of times the dice must be rolled and this value must be greater than
50
.print
the number of times a particular number was obtained when the dice was rolled. Make use ofrandint
fromrandom
module.
Summary
 A module is a script that we can reuse in another code  look at the advantages of using a function in
Excercise 12 a (Functions)
 use the
import
keyword to bring in a module 
from module import *
imports all the objects in the module 
from module import some_objects
import these objects 
from module import object as obj
imports object given a new nameobj
from module
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