Lecture: Functions in Python

def hello():
    print('Hello')
    print('Hi')
    print('Tom')
	

hello()
hello()

Lecture: Passing arguments to function

def add():
    a= 10
    b= 20
    print(a+b)

add()

def add(a,b):
    print(a+b)

add()

add(10,20)
add(20,40)
add(34,23)

Lecture: Keyword arguments

def speed(distance,time):
    s = distance/time
    return s

avgspeed = speed(100,2)
print(avgspeed)

avgspeed = speed(2,100)
print(avgspeed)

Calling the above function with keyword arguments

avgspeed = speed(time=2,distance=100)
print(avgspeed)

Lecture: Default parameters

def area(pi,radius):
    a = pi * radius * radius
    return a

circle_area = area(3.14,10)
print(circle_area)

Making the pi argument as default argument

def area(radius,pi=3.14):

Now even if you dont pass in the value of PI in the function call it still works fine

circle_area = area(10)

Passing pi as 3.15

circle_area = area(10,3.15)

Lecture: Making function return a value

def add(a,b):
    c= a+b
    return c

result = add(10,20)
print(result)

Lecture: calling a function inside another function

def add(a,b):
    return a+b

def square(c):
    return c*c

result = square(add(2,3))
print(result)

Lecture: Returning multiple values from a function

def circle(r):
    area = 3.14*r*r
    circumfurence = 2*3.14*r
    return area,circumfurence

# calling the function and extracting the value
a,c = circle(10)
print(f"Area of a circle is {a}, circumference is {c}")

Lecture: Passing list to a function

def sum(numbers):
    total = 0
    for number in numbers:
        total = total + number
    return total

result = sum([1,2,3,4,5])
print(result)

Lecture: Returning a list

def remove_duplicates(numbers):
    # create a new list which does not contain duplicates
    new_list =[]
    for number in numbers:
        if number not in new_list:
            new_list.append(number)
    return new_list

list = [1,2,3,4,3,4,5,2,1,7,8,9]
result = remove_duplicates(list)
print(result)

A simpler way is by using set()

Take the list, pass it to the set it will remove the duplicate elements.

Then convert the set back into a list:

def remove_duplicates(lst):
    return list(set(lst))

Lecture: Global & Local Variables

def add():
    count =1
    print(count)    
    
def sub():
    count =2
    
    print(count)
    
sub()
add()

Lecture: Accessing global variable inside a function

count = 10

def increment():
    global count
    count = count + 1
    print(count)
    
    
increment()

Lecture: Check if a string is palindrome

word = "panasonic"
# treat a string like a list
print(word[0])

# get the length of string
l = len(word)

# loop through all the items from the start
print('Printing the string straight')
for i in range(l):
    print(word[i])
    
# loop through the items in reverse
print('Printing the string in reverse')
for i in range(l):
    print(word[l-i-1])
    
#comparing and returning if palindrome
palindrome_flag = True
for i in range(l):
    if word[i] != word[l-i-1]:
        palindrome_flag = False
        break
    else:
        palindrome_flag = True

if palindrome_flag:
    print("The string is a palindrome")
else:
    print('The string is not a palindrome')
    

#converting the above code into a function
def check_palindrome(word):
    #get the length of the string
    l = len(word)
    for i in range(l):
        if word[i] != word[l-i-1]:
            return False
    return True
    
# call the above function
print(check_palindrome("racecar"))

Lecture: EMI Calculator

#formula to calculate emi is: P x R x (1+R)^N / [(1+R)^N-1]
#P: Principal loan amount = INR 10,000,00

#N: Loan tenure in months = 120 months

#R: Interest rate per month [7.2/12/100] = 0.006

def emi_calculator(principal,rate,time):
    #calculate the monthly rate
    r = rate/12/100
    emi = (principal * r * (1+r)**time) / ((1+r)**time -1 )
    return emi

#checking the function
print(emi_calculator(4858900, 8.75, 240))

Lecture: Factorial Using Recursion in Python

Python code to calculate factorial:

def factorial(number):
    if number ==1:
        return 1
    else:
        return number * factorial(number-1)
    
print(factorial(4))

#how the iterations work
#factorial(4) => return 4 * factorial(3)
#factorial(3) => return 3 * factorial(2)
#factorial(2) => return 2 * factorial(1)
#factorial(1) => return 1

Lecture: Variable length positional arguments

def add(*args):
    sum = 0
    for n in args:
        sum = sum+n
    print(sum)

add()
add(10)
add(20, 30)
add(40, 50, 60)

Lecture: Variable length keyword arguments

def product(**kwargs):
    for key, value in kwargs.items():
        print(key+":"+value)

product(name='iphone', price="700")
product(name='iPad', price="400", description="This is an ipad")

Lecture: Decorators in Python

def chocolate():
    print('chocolate')
chocolate()

def chocolate():
    print('chocolate')

# this decorator function accepts function as argument

def decorator(func):
    # inside the decorator function we have another function
    def wrapper():
        print('Wrapper up side')
        # now here I call the func
        func()
        print('Wrapper down side')
    # now the decorator needs to return this wrapper
    return wrapper

# now to call the functions, i first call the decorator and then pass chocolate inside it
# then assign the function back to the previous main function i.e chocolate
# finally call the chocolate function
chocolate = decorator(chocolate)
chocolate()

def decorator(func):
    # inside the decorator function we have another function
    def wrapper():
        print('Wrapper up side')
        # now here I call the func
        func()
        print('Wrapper down side')
    # now the decorator needs to return this wrapper
    return wrapper

@decorator
def chocolate():
    print('chocolate')

chocolate()

Lecture: Reusing decorators

@decorator
def cake():
    print('cake')

cake()

Lecture: Decorating functions which accept arguments

@decorator
def cake(name):
    print('cake'+name)

cake("apple")

def decorator(func):
    def wrapper(name):
        print('Wrapper up side')
        func(name)
        print('Wrapper down side')
    return wrapper

chocolate()

def decorator(func):
    def wrapper(*args, **kwargs):
        print('Wrapper up side')
        func(*args, **kwargs)
        print('Wrapper down side')
    return wrapper

@decorator
def chocolate():
    print('chocolate')

@decorator
def cake(name):
    print('cake'+name)

chocolate()
cake("Mango")

Lecture: Decorating functions that return a value

def total(price):
    # Let's assume there was some code here which calculated the total amount
    return price

Now lets create a decorator for it:

def summer_discount_decorator(func):
    def wrapper(price):
        # take the value inside the total and return
        func(price)
        return func(price/2)
    return wrapper

Entire code:

def summer_discount_decorator(func):
    def wrapper(price):
        # take the value inside the total and return
        func(price)
        return func(price/2)
    return wrapper

@summer_discount_decorator
def total(price):
    # Let's assume there was some code here which calculated the total amount
    return price

print(total(20))