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Quick Python Overview

Dec 17, 20243 min read

Python Data Types:

Type Casting

Two types of typecasting:

  1. Implicit i.e. int→float
print(10 == 10.00) #True. But why it is true?
print(10 + 10.00) #20.00
  1. Explicit i.e. str→int

Variable Scope:

Scope Hierarchy in Python:

  1. Built-In Scope: Contains built-in names and is always available.
  2. Global Scope: Names defined at the top level of a script or module.
  3. Enclosing Scope: Names in the local scopes of enclosing functions (non-local but also not global).
  4. Local Scope: Names defined within a function.

Primitive vs Non-Primitive Data types

  • Primitive Data Types: int, float, bool, str
  • Non-Primitive Data Types: list, tuple, dict, set, frozenset

Data Structure in Python

Python has the following built-in data structures: List, dictionary, tuple and set. These are all considered non-primitive data structures, meaning they are classed as objects.

Mutability and Immutability

Mutability refers to data inside the data structure that can be modified. For example, you can either change, update, or delete the data when needed. A list is an example of a mutable data structure. The opposite of mutable is immutable. An immutable data structure will not allow modification once the data has been set. The tuple is an example of an immutable data structure.

Three way of iterating a Dictionary

args vs kwargs

>>> def sum_of(**kwargs):
...     sum = 0
...     for key, value in kwargs.items():
...             sum += value
...     return sum
...
>>> print(sum_of(a=10,b=12,c=13))
35

with args we can pass any number of non-Keyword variable with kwargs we can pass any number of Keyword arguments

Types of Error in Python

  1. Syntax Error
  2. Exception Error: Exception Error occur in the runtime.

File Handling

There are four modes of handling file in Python:

  1. r - open for reading file
  2. r+ - open for reading and writing
  3. w - open for writing
  4. a - open for editing and appending

with open closes the file automatically

Procedural Programming Paradigm

Advantages of Procedural Programming: Disadvantage of Procedural Programming:

Traditional VS Pure Functions

Functional Programming Paradigm

In python function is first class citizen. That means they are on the same level of string and numbers. Advantages of Functional Programming:

Benefits of Pure Functions

map and filter()

map(compare_function, list) ⇒ None ⇒ None ⇒ X ⇒ Y ⇒ None

filter(compare_function, list) ⇒ X ⇒ Y

Comprehensions

Comprehensions in Python are a way to create a new sequence from an already existing sequence. There are four main types of comprehensions in Python:

  1. List comprehension
  2. Dictionary comprehension
  3. Set comprehension
  4. Generator comprehension
List comprehension

The syntax for list comprehension is:

[ <expression> for x in <sequence> if <condition> ]
Dictionary comprehension

The syntax for dictionary comprehension is:

dict = { key:value for key, value in <sequence> if <condition> }
Set comprehension

The syntax for Set comprehension is:

{ <expression> for x in <sequence> if <condition> }
Generator comprehension

Generator comprehensions are also very similar to lists with the variation of using curved brackets instead of square brackets. They are also more memory efficient as compared to list comprehensions.

The syntax for Generator comprehension is:

( <expression> for x in <sequence> if <condition> )

Order in Which Module is Searched

  1. Current Directory Path
  2. Built in Module directory
  3. PYTHONPATH
  4. Installation dependent default directory

Working Module From Folder

import sys
sys.path.insert(1, "/Users/abrarfahim/Developer/Python/temp/demo")
import names
print(names.names)

Graph View

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