자주하는 실수

How to remove elements in a Python List while looping

a = [1, 2, 2, 3, 4]


def even(x):
    return x % 2 == 0


for item in a:
    if even(item):
        a.remove(item)

print(a)

결과: [1, 2, 3]

참고: https://www.python-engineer.com/posts/remove-elements-in-list-while-iterating/

 

 

Mutable Default Arguments

def append_to(e, to=[]):
    to.append(e)
    return to


my_list = append_to(12)
print(my_list)

my_other_list = append_to(42)
print(my_other_list)

출력결과

[12]
[12, 42]

 

Late Binding Closure

for multiplier in [lambda x: i * x for i in range(5)]:
    print(multiplier(2))

출력결과

8
8
8
8
8

 

Global Variable

x = 3


def f():
    y = x + 1
    x = 2


f()

결과

UnboundLocalError: local variable 'x' referenced before assignment

 

 

참고: https://python-guide-kr.readthedocs.io/ko/latest/writing/gotchas.html