Python Generators/List comprehension comparison

import time, sys

genstartime = time.perf_counter()

gensquares = (x**2 for x in range(500000))

# print(time.perf_counter() - genstartime, type(gensquares))

gencompstartime = time.perf_counter()

finalgenlist = [square for square in gensquares]

print(

    "Generator with list comprehension. Generator time:",

    time.perf_counter() - gencompstartime,

    "Final time:",

    time.perf_counter() - genstartime,

)

genstartime = time.perf_counter()

gensquares = (x**2 for x in range(500000))

# print(time.perf_counter() - genstartime, type(gensquares))

gencompstartime = time.perf_counter()

finalgenlist = list(gensquares)

print(

    "Generator with list(). Generator time:",

    time.perf_counter() - gencompstartime,

    "Final time:",

    time.perf_counter() - genstartime,

)

print('Memory size of generator  in bytes:', sys.getsizeof(gensquares),

      'Memory size of list  in bytes:', sys.getsizeof(finalgenlist))

# An important thing to note is that generators iterate over an object lazily,

# meaning they do not store their contents in memory.

# listfromgen = list(gensquares)

# print(listfromgen, len(listfromgen), sys.getsizeof(listfromgen)) # [] 0 56

# print(len(finalgenlist)) # list kept in memory, len equal to range

liststartime = time.perf_counter()

listsquares = [x**2 for x in range(500000)]

print(

    "Simple list comprehension", time.perf_counter() - liststartime, type(listsquares)

)

# print( 'Memory size after list comprehension in bytes:', sys.getsizeof(listsquares))

 

Results with Python 3.11.4:

Generator with list comprehension. Generator time: 0.09394780000002356 Final time: 0.09395289999883971
Generator with list(). Generator time: 0.0871331000016653 Final time: 0.08714600000166683
Memory size of generator in bytes: 208 Memory size of list in bytes: 4167352
Simple list comprehension 0.06546270000035292 <class 'list'>

Generator with list comprehension. Generator time: 0.08868479999728152 Final time: 0.08870200000092154
Generator with list(). Generator time: 0.08478610000020126 Final time: 0.08480150000104913
Memory size of generator in bytes: 208 Memory size of list in bytes: 4167352
Simple list comprehension 0.06996629999775905 <class 'list'>

Generator with list comprehension. Generator time: 0.08237219999864465 Final time: 0.08237809999991441
Generator with list(). Generator time: 0.09145460000218009 Final time: 0.09146870000040508
Memory size of generator in bytes: 208 Memory size of list in bytes: 4167352
Simple list comprehension 0.0625220999972953 <class 'list'>