#Python-Advance

Python DateTime module

The datetime classes are categorize into 6 main classes –

• date
  • Its attributes are year, month and day
• time
  • Its attributes are hour, minute, second, microsecond and tzinfo

Handling timezone in Python

UTC, or Coordinated Universal Time, is the primary time standard by which the world regulates date and time.

• astimezone() –> it helps to convert the time of a particular time zone into another time zone
• localtime() –> it helps to get the current local time

Python collection module

• There are 4 basic collection data types
  • List, Tuples, Sets, Dictionary
• Specialised collection data types
  • Counter, OrderedDict, UserDict, UserList, UserString
  • defaultdict, deque, namedtuple(), Chainmap

Deepcopy and Shallow copy

• In case of shallow copy, a reference of object is copied in other object.
  • It means that any changes made to the copied object do reflect in the original object
  • External object id changes but Internal object id remains same
• In case of deep copy, a copy of object is copied in other object.
  • It means that any changes made to the copied object do not reflect in the original object
  • External and internal object ids changes

Value equality vs identity

• Value –> equivalent contents
• Identity –> same object

Binding Names to Objects

p = [1,2,3]
q = [1,2,3] 
p == q  # --> True    --> val is same
p is q  # --> False   --> not same obj

a = "first"
b = "first"
a is b # --> True

• NOTE:
  • Immutable object (str, int tuple) refers to same obj if values are same
  • Mutable obj always create new object

Pass by object reference

• Python uses neither Pass by Value nor Pass by Reference
• But it uses Pass by Object Reference

First Class functions in Python

• In Python when functions treated like any other variable then they are term as First-class functions
• Properties of first class functions:

  • Assign to a variable.
  • Pass the function as a parameter to another function.
  • Return a function from another function.

Nested function

• Function defined inside another function –> nested function
• Nested functions are able to access variables of the enclosing scope.

def print_msg(msg):
  def printer():
    print(msg)
  printer()

print_msg("Hello")
# Output: Hello

Python Decorators

• It’s a very powerful and useful tool in Python
• It allows to add functionality to an existing function or class.

7. Multi-threading

Multithreading allows you to break down an application into multiple sub-tasks and run these tasks simultaneously.

If you use multithreading properly, your application speed, performance, and rendering can all be improved.

Multithreading is defined as the ability of a processor to execute multiple threads concurrently.

Multi Processing

Multiprocessing refers to the ability of a system to support more than one processor at the same time.

Applications in a multiprocessing system are broken to smaller routines that run independently. The operating system allocates these threads to the processors improving performance of the system.