Read: Class 08 Summary :

List Comprehensions in Python

• List comprehensions provide a concise way to create lists.It consists of brackets containing an expression followed by a for clause, then zero or more for or if clauses. The expressions can be anything, meaning you can put in all kinds of objects in lists.
• The list comprehension always returns a result list.

• The list comprehension starts with a ‘[‘ and ‘]’, square brackets, to help you remember that the result is going to be a list.

• The basic syntax uses square brackets :

  [ expression for item in list if conditional ]
  

• This is equivalent to:

for item in list:
    if conditional:
        expression

• Example :
• Print numbers only from a given string
• This example show how to extract all the numbers from a string.

string = "Hello 12345 World"
numbers = [x for x in string if x.isdigit()]
print numbers
>> ['1', '2', '3', '4', '5']

• Change x.isdigit() to x.isalpha() if you don’t want any numbers.

Primer on Python Decorators

• a decorator is a function that takes another function and extends the behavior of the latter function without explicitly modifying it.
• In Python, functions are first-class objects. This means that functions can be passed around and used as arguments, just like any other object (string, int, float, list, and so on).
• It’s possible to define functions inside other functions. Such functions are called inner functions.