For generators, why write 'yield'? Why not write 'return' or 'print'? Could someone explain the concept of generators?

Answer 1

The generator in python allows you to declare a function that is used like an iterator. It is used so that you don't have to create additional variables where you have to iterate it.

for example:

this is using the conventional way:

def func(n):
num = 0
nums = []
while num < n:
nums.append(num)
num += 1
return nums
example=sum(func(10000))
print(example)

the same using a generator:

def func(n):
num = 0
while num < n:
yield num
num += 1
example=sum(func(10000))
print(example)

Note: the first example builds and returns a list, but the second example yields items instead of returning a list.

Both give the final answer of 49995000, but the first example stores all the items in a list that takes a lot of memory while the second example saves a ton.

Hope this helps.

Answer 2

# you will get a reasonable starting introduction here.
# https://jeffknupp.com/blog/2013/04/07/improve-your-JUMP_LINK__&&__python__&&__JUMP_LINK-yield-and-generators-explained/

# A simple generator example is

def a_yielding_function():
num = 0
while 1:
yield num
num += 4

the_generator = a_yielding_function()

# type will quickly show you wether you are looking at
# a function or a generator class object as you try to
# construct them yourself or look at peoples examples.
print(type(the_generator))

for i in range(6):
print(next(the_generator))

Answer 3

The yeild kyword simply return a result to caller without destroying local variables. In case of return it terminate the function and destroy local variables