Generators in Python

Why do we need a Generator?

Generator is easy to define but it is a little bit difficult to understand,Generator is used for the iterator but in a different way,Generator is nothing but just a simple function.

How to create a generator?

• Generators are normal functions which return an iterator of items instead of a simple object.
• The generators is define by the one or more than one yield statement.
• A generator has a parameter, which we can call and it generates a series of numbers. As a difference with functions, which return a complete array, a generator yields one value at a time as an element of an array and keeps returning each value at a time, consequently acquiring less memory.
• If a function uses at least one ‘yield’ keyword then that function becomes a generator function.

Return Vs Yield statement:

• Yield and returns both return some values.
• The difference is that,
  ○ Returns: only return a single value and terminate the corresponding function.
  ○ Yield: It pauses the function and saves all its states and later proceeds with successive calls.

Example: Print Square of first n natural number

def sq_gen(n):
    number=1
    while True:
        yield number
        if number==n:
            return
        else:
            number +=1

n= int(input("Enter end of range: "))
sq_arr=[]
for i in sq_gen(n):
    sq_arr.append(i*i)
print(sq_arr)

Output:

Python 3.8.4 (tags/v3.8.2:7b3av59, Feb 25 2020, 23:03:10) [MSC v.1916 64 bit (AMD64)] on win32

>>> 
================== RESTART: C:/Users/PC/Desktop/Hello.py ================
Enter end of range: 10
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]