Advance python programming

Introduction to Advanced
Python Programming
Jagdish D. Chavan
Data Scientist| Emerging Industry Trainer|
Certified Python, Data Science Trainer| AI,ML,DL Expert
Github | Linkedin

Functional Programming
● Functional programming decomposes a problem into a set of functions.
● Ideally, Functions only take inputs and produce output, and don’t have any internal state that affects
the output produced for a given input.
● Functional techniques common to many languages : such as lambda, map, reduce.
*Note:- for more code & projects follow me on Linkedin | Github

Anonymous Functions or Lambdas
● Anonymous functions are the functions without name.
● Anonymous functions are not defined using ‘def’ keyword.
● They are defined using the keyword lambda hence also called as lambda functions.

Syntax for Lambda function.
Syntax for normal function
def function_name(parameters):
function_block
return expression
Example:- Square of Given value
code
def square(x): #declaring function
return x*x
square(9) #calling a function
Output
81
Syntax for Lambda Function
Lambda argument_list : expression
Example:- Square of Given value
Code
y = lambda x: x*x #declaring
value = y(9) #calling a function
print(value)
Output
81

Syntax for Lambda function.
Syntax :- Lambda <argument_list> : <expression>
f = lambda x: x*x
● Observe the keyword ‘lambda’. This represents that an anonymous function is being created.
● ‘X’ is argument of function followed by colon(:) representing beginning of function containing expression x*x.
● Normally, if a function returns some value, we assign that value to a variable as:
y = square(9)
● but , lambda function returns a function and hence they should to assign to function as:
f = lambda x:x*x
● Here ‘f’ is the function name to which lambda expression is assigned. Now if we call the functions f() as: value =f(5)

Properties of Lambda function.
● We can pass n number of arguments in lambda function, but only one expression is allowed.
● They return the result implicitly, hence we should not write any ‘return’ statements in the
lambda functions.
● Because a lambda functions is always represented by a function, we can pass a lambda function
to another function .
● It means we are passing a function (i.e lambda ) to another function, making processing data
very easy lambda function are generally used with functions like filter(), map(), or reduce().

Exercise no 1.
1) Write a Python Program to create a lambda function that returns a square value of given
number.
2) Write a Python Program to calculate the sum of two numbers using lambda function
3) Write a Python Program to find bigger number in two given number using Lambda Function .
Note:- for more examples and answers please do visit Advance Python Programming

Using Lambda with Filter() Function.
● The filter() function is useful to filter out the elements of a sequence depending on the result of
a function.
● We should supply a function and a sequence to the filter() function as
Syntax :-filter(function, sequence)
● function:- represent the function name that may return either True or False.
● Sequence:-represents a list, string or tuple.
● The ‘function’ is applied to every element of the ‘sequence’ and when function returns True, the
element is extracted otherwise it is ignored.

Using Lambda with Filter() Function.
Example
#write a python Program using lambda function that returns even number from the list.
lst = [10,23,45,46,70,99]
lst1 = list(filter(lambda x:(x%2==0),lst))
print(lst1)
Output
[10, 46, 70]

Using Lambda with map() Function.
● map () function acts on each element of the sequence and perhaps changes the element
● The syntax of map() function is as follow
Syntax:- map(function, sequence)
● The function performs specific operations on all the elements of the sequence and modified
element are returned which can be stored in another sequence.
Example
#write a python program using lambda function that returns squares of elements in a list.
lst = [1,2,3,4,5]
lst1 = list(map(lambda x: x*x, lst))
print(lst1)
Output
[1, 4, 9, 16, 25]

Using Lambda with map() Function.
Exercise
1) Write a Python program to find the products of elements of two different lists using lambda
function.
Note:- for more examples and answers please do visit Advance Python Programming

Using Lambda with reduce() Function.
● reduce () function reduces a sequence of elements to a single value by processing elemets
according to a function supplied.
● Syntax :- reduce(function, sequence)
Example
#write a Python program using lambda function to calculate product of elements of list
from functools import *
lst = [1,2,3,4,5]
result = reduce(lambda x,y: x*y,lst)
print(result)
Output
120

Advance python programming

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