>>> listcomp = ['Hello' for i in range(3)]

>>> genexpr = ('Hello' for i in range(3))

​

>>> even_squares = (x * x for x in range(10)

                    if x % 2 == 0)

​

#Generator expressions

​

#List comprehension is greedy evaluation, create lists immediately when execute it

#Generator expressions is lazy evaluation, creates an iterable generator object on demand

#Generator uses () instead of []

#Syntax order changes slightly compared to list comprehension

​

numbers = [1, 2, 3, 4, 5, 6, 7, 8]

for val in (x**2 for x in numbers if x%2 != 0):     # note the () instead of []

    print(val, end = " ")

#1 9 25 49 

>>> genexpr = ('Hello' for i in range(3))

>>> list(genexpr)

['Hello', 'Hello', 'Hello']

​

>>> iterator = ('Hello' for i in range(3))

>>> for x in iterator:

...     print(x)

'Hello'

'Hello'

'Hello'

​

def generator():

    for item in collection:

        yield expression

​

>>> for x in even_squares:

...     print(x)

0

4

16

36

64

​