Python Advance

Post description

Lambda

Lambda is a keyword in Python used to define functions, more specifically Anonymous Functions
lambda arguments: expression

sum_fun = lambda a,b : a+b
sum_fun(2,3)

5

Map

• A function that applies a given function to each item of an iterable and returns an iterator.
• It provides a faster way to transform an iterable based on the given condition.
  map(function, iterable)

sq = lambda x:x**2
list(map(sq,[1,2,3,4]))

[1, 4, 9, 16]

Filter

• It helps in extracting items from an iterable based on the given condition.
  filter(function, iterable)

def is_even(num):
    return num % 2 == 0

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
list(filter(is_even, numbers))

[2, 4, 6, 8, 10]

Reduce

• It applies a function cumulatively/successively on each item of an iterable and returns a single value
  reduce(function, iterable, [, initializer])

from functools import reduce
sum_fun = lambda x,y:x+y
reduce(sum_fun,[1,2,3,5])

11

Generator

Generators are a type of iterable, similar to lists or tuples, but with a key difference. Instead of storing all the values in memory at once, generators generate values on-the-fly as they are needed.

This makes them memory-efficient and allows them to handle large data sets or infinite sequences.

The yield statement pauses the function and returns the current value, and the function’s state is saved

def num_generator(n):
    for i in range(n):
        yield i
num = num_generator(5)
print(num)

# Iterating over the generator
for i in num:
    print(i)

<generator object num_generator at 0x000001BDBF0E3990>
0
1
2
3
4

Decorator

Decorator is a design pattern that allows you to modify or extend the behavior of a function or class without directly modifying its source code.

Decorators are implemented using the “@” symbol followed by the decorator function or class name, which is then placed directly before the function or class definition.

def main_fun(func,a=10):
    print("start main function")
    func()
    print("end main function")
    return 1

@main_fun
def fun():
    print("start decorator fun")
    
fun

start main function
start decorator fun
end main function





1

Class

init function

• In Python, __init__()is a special method (also known as a constructor) that is automatically called when you create an object of a class. It is used to initialize the attributes of the object.

• Inside the init() method, you can define statements that initialize the attributes of the object

Inheritance

Inheritance allows us to define a class that inherits all the methods and properties from another class.

Parent class is the class being inherited from, also called base class.

Child class is the class that inherits from another class, also called derived class.

When you add the __init__() function, the child class will no longer inherit the parent’s __init__() function.

class Student(Person):
  def __init__(self, fname, lname):

To keep the inheritance of the parent’s __init__() function, add a call to the parent’s __init__() function:

class Student(Person):
  def __init__(self, fname, lname):
    Person.__init__(self, fname, lname)

super() function that will make the child class inherit all the methods and properties from its parent

class Student(Person):
  def __init__(self, fname, lname):
    super().__init__(fname, lname)

class Person:
    def __init__(self, fname, lname):
        self.firstname = fname
        self.lastname = lname

    def printname(self):
        print(self.firstname, self.lastname)

class Student(Person):
    def __init__(self, fname, lname, year):
        super().__init__(fname, lname)
        self.graduationyear = year

    def printstd(self):
        print("Welcome", self.firstname, self.lastname, "to the class of", self.graduationyear)

x = Student("Mike", "Olsen", 2023)
x.printstd()

Welcome Mike Olsen to the class of 2023

RegEx

1. Matches any digit (0-9).
2. : Matches any non-digit character.
3. : Matches any alphanumeric character (a-z, A-Z, 0-9, and underscore _).
4. : Matches any non-alphanumeric character.
5. : Matches any whitespace character (space, tab, newline).
6. : Matches any non-whitespace character.
7. .: Matches any character except a newline.
8. ^: Matches the start of a string.
9. $: Matches the end of a string.
10. []: Matches any character inside the brackets. For example, [aeiou] matches any vowel.
11. [^]: Matches any character not inside the brackets. For example, [^aeiou] matches any consonant.
12. *: Matches zero or more occurrences of the previous pattern.
13. +: Matches one or more occurrences of the previous pattern.
14. ?: Matches zero or one occurrence of the previous pattern.
15. {n}: Matches exactly n occurrences of the previous pattern.
16. {n,}: Matches n or more occurrences of the previous pattern.
17. {n,m}: Matches between n and m occurrences of the previous pattern.
18. |: Matches either the pattern on the left or the pattern on the right.
19. (): Groups patterns together.
20. (?i): Performs a case-insensitive match.
21. (?m): Enables multiline matching.