python - 手动替换列表中的元素

Question

例子：

a = [1,2,3,2,4,2,5]
for key in a:
    if key == 2:
        key = 10
print key

结果：[1,10,3,10,4,10,5]

我需要 Python 手动“询问”要替换哪些元素。

Answer 1

>>> a = [1,2,3,2,4,2,5]
>>> a[:] = [10 if x==2 else x for x in a]
>>> a
[1, 10, 3, 10, 4, 10, 5]

如果要替换多个项目，请考虑使用 dict：

>>> dic = {2 : 10}
>>> a[:] = [dic.get(x,x) for x in a]
>>> a
[1, 10, 3, 10, 4, 10, 5]

Answer 2

您正在寻找enumerate()：

for indx, ele in enumerate(a):
    if ele == 2:
        a[indx] = 10
print a

印刷：

[1, 10, 3, 10, 4, 10, 5]

---

如果您要更改的值是输入，那么只需执行以下操作：

change = map(int, raw_input("What number do you want to change in the list? And what number should it be? Separate both numbers with a space ").split())
for indx, _ in enumerate(a):
    if change[0] == 2:
        a[indx] = change[1]

或作为列表理解（如果您喜欢此解决方案，请支持 Ashwini 的 :)）：

change = map(int, raw_input("What number do you want to change in the list? And what number should it be? Separate both numbers with a space ").split())
[change[1] if x == change[0] else x for x in a]