List Comprehensions

[snippsat]

The performance difference is small,if want to know just use timeit.
Here are all 3 and also tested with PyPy.:cool: 

import timeit

ordinary_loop = '''\
lst = ['1', '500', '999']
l = []
for i in lst:
    l.append(int(i))
'''
# 21.14 sec
# PyPy 3 sec

list_comp = '''\
lst = ['1', '500', '999']
[int(i) for i in lst]
'''
# 20.54 sec
# PyPy 2.59 sec

_map = '''\
lst = ['1', '500', '999']
list(map(int, lst))
'''
# 22.6 sec
# PyPy 3.5 sec

print(timeit.Timer(stmt=_map).timeit(number=10000000))