如何在列表理解中修改Python列表的最后一个元素？

Question

I have a code segment like following which throws an invalid syntax error:

lst = [0, 0, 0]
new_lst = [lst[-1] = i + 1 for i in range(3)]

Basically, I want new_lst to be list of lists, where every list will be lst but the last element changed. Any ideas how to do this in Python?

Answer 1

You can only make assignments when they are stand-alone statements Ie not within a list comprehension. Other examples of this would be in control statements like if s or for s

In [945]: lst = [0, 0, 0]

In [946]: new_lst = [lst[:-1] + [i + 1] for i in range(3)]

In [947]: new_lst
Out[947]: [[0, 0, 1], [0, 0, 2], [0, 0, 3]]

lst[:-1] takes every element from lst except for the last and [i + 1] will be appended to the end of the list