PYTHON

generator expressions python

>>> even_squares = (x * x for x in range(10)
                    if x % 2 == 0)

Python Generator Expression

# Initialize the list
my_list = [1, 3, 6, 10]

# square each term using list comprehension
list_ = [x**2 for x in my_list]

# same thing can be done using a generator expression
# generator expressions are surrounded by parenthesis ()
generator = (x**2 for x in my_list)

print(list_)
print(generator)

generator expressions python

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

generator expressions python

>>> genexpr = ('Hello' for i in range(3))
>>> list(genexpr)
['Hello', 'Hello', 'Hello']

generator expressions python

>>> iterator = ('Hello' for i in range(3))
>>> for x in iterator:
...     print(x)
'Hello'
'Hello'
'Hello'

generator expressions python

def generator():
    for item in collection:
        yield expression

generator expressions python

>>> for x in even_squares:
...     print(x)
0
4
16
36
64

generator expression python

#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