What is a generator in python???

Simply speaking, a generator is a function that returns an object (iterator) which we can iterate over (one value at a time).

Difference between generator function and object???

For generator function:

If the body of a def contains yield, the function automatically becomes a generator function.

Example:

**def** simpleGeneratorFun():
	**yield** 1
	**yield** 2
	**yield** 3

For generator object:

Generator functions return a generator object.

Example:

**for** value **in** simpleGeneratorFun():
	**print**(value)

or

x = simpleGeneratorFun()
while True:
    try:
        print(x.next())
    except StopIteration:
        break

Why we use generator???

• Easy to Implement

  Example to implement a sequence of power of 2 using an iterator class.

  class PowTwo:
      def __init__(self, max=0):
          self.n = 0
          self.max = max
  
      def __iter__(self):
          return self
  
      def __next__(self):
          if self.n > self.max:
              raise StopIteration
  
          result = 2 ** self.n
          self.n += 1
          return result
  

  or

  def PowTwoGen(max=0):
      n = 0
      while n < max:
          yield 2 ** n
          n += 1
  

• Memory Efficient

  Generator implementation of such sequences is memory friendly and is preferred since it only produces one item at a time.

• Represent Infinite Stream

  Since generators produce only one item at a time, they can represent an infinite stream of data.