def even_odd(num):
    if num%2==0:
        print("number is even")
    else:
        print("number is odd")

even_odd(24)

number is even

def hello(name, age=29): # name  is positional argument and age is keyword argument
    print("my name is {} and age is {}".format(name, age))

hello('sid')

my name is sid and age is 29

hello('sid',20)

my name is sid and age is 20

def hello(*args, **kwargs):
    print(args)
    print(kwargs)

hello('sid','saxena',age=29,dob=2000)

('sid', 'saxena')
{'age': 29, 'dob': 2000}

lst=['sid','saxena']
dict_args={'age': 20 ,'dob':2000}

hello(*lst,**dict_args)

('sid', 'saxena')
{'age': 20, 'dob': 2000}

lst = [1,2,3,4,5,6,7]

def evenoddsum(lst):
    even_sum=0
    odd_sum=0
    for i in lst:
        if i%2==0:
            even_sum += i
        else:
            odd_sum += i
            
    return even_sum,odd_sum

evenoddsum(lst)

(12, 16)

Lambda functions

def addition(a,b):
    return a+b               # Single expression can only be converted

addition(4,5)

9

addition = lambda a,b:a+b

addition(5,6)

11

def even(num):
    if num%2==0:
        return True

even(24)

True

even1 = lambda num:num%2==0

even1(12)

True

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

add(1,2,3)

6

three_add = lambda x,y,z:x+y+z

three_add(1,2,3)

6

Map Function

def even_odd(num):
    if num%2==0:
        return True
    else:
        return False

even_odd(23)

False

lst=[1,2,3,4,5,6,7,8] # apply same function on multiple values

map(even_odd,lst) # in order to instantiate convert it into a list ## memory is not intialised yet

<map at 0x2a398c7e248>

list(map(even_odd,lst))

[False, True, False, True, False, True, False, True]

list(map(lambda num:num%2==0,lst))

[False, True, False, True, False, True, False]

Filter function

 def even(num):
        if num%2==0:
            return True

lst=[1,2,3,4,5,6,7]

list(filter(even,lst)) # return elements which satisfy the condition

[2, 4, 6]

list(filter(lambda num:num%2==0,lst))

[2, 4, 6]

List Comprehension

provide a concise way to create lists, It consists of braces containing an expression followed by for clause, then zero or more for or if clauses

lst1=[]

def lst_square(lst):
    for i in lst:
        lst1.append(i*i)
    
    return lst1

lst_square([1,2,3,4,5,6,7])

[1, 4, 9, 16, 25, 36, 49]

lst=[1,2,3,4,5,6,7]

#list comprehension

[i*i for i in lst ]

[1, 4, 9, 16, 25, 36, 49]

list1=[i*i for i in lst ]
print(list1)

[1, 4, 9, 16, 25, 36, 49]

[i*i for i in lst if i%2==0]

[4, 16, 36]

String Formatting

print("hello")

hello

str="hello"

print(str)

hello

def greetings(name):
    return "hello {}".format(name)

greetings('sid')

'hello sid'

def welcome_email(firstname,lastname):
    return "welcome {}. is your last name is {}".format(firstname,lastname) # order can not be altered

welcome_email('sid','saxena')

'welcome sid. is your last name is saxena'

def welcome_email(name,age):
    return "welcome {name}. is your age is {age}".format(age=age,name=name) # now ordering can alter

welcome_email('sid',20)

'welcome sid. is your age is 20'

def welcome_email(name,age):
    return "welcome {name1}. is your age is {age1}".format(age1=age,name1=name)

welcome_email('sid',20)

'welcome sid. is your age is 20'

List Iterables vs Iterators

lst = [1,2,3,4,5,6,7] # this whole list is getting initialised in the memory 

for i in lst:
    print(i)

list1=iter(lst) #but in case of iterators whole listdose not get stored in memory it will get accessed only via next

list1

<list_iterator at 0x2a3996beb08>

next(list1)

1

next(list1)

2

 for i in lst1:
        print(i)

1
4
9
16
25
36
49