Python 列表 [-1:] 和 [-1] 的区别

x = [1, 2, 3]

print(x[-1])  # --> 3
print(x[-1:]) # --> [3]

输出：

3
[3]

print("abcd"[-1])  # --> "d"
print("abcd"[-1:]) # --> "d"

输出

d
d

The only advantage of using for example s[-1:] or s[:1] with a string instead of s[-1] and s[0] is that the slice expressions will not raise a runtime error when acting on an empty string (something that element access does)… this may allow code simplification:

if len(s) > 0 and s[0] == '*': ...
if s[:1] == '*': ...

参考

https://stackoverflow.com/questions/33841023/is-there-any-difference-between-python-list-slicing-1-and-1