如何对未知长度的嵌套列表中各子列表的最后元素求和？

Hey there! Let's break down what's causing your error and fix this up quickly.

What's Wrong with Your Current Code? #

The issue is in this line:

addList.append(eglist[-1])

eglist[-1] grabs the last entire sublist from your main list (in your example, that's ["b",2,3.4]), not the last element of the current sublist i you're looping through. That's why addList ends up filled with lists instead of the float values you need—hence the TypeError when trying to sum them.

Fixed Version of Your Code #

Just change eglist[-1] to i[-1] to target the last element of each individual sublist:

eglist = [["a", 1, 2.3],["b",2,3.4]]
addList = []
for i in eglist:
    addList.append(i[-1])  # This gets the last element of the current sublist
total = sum(addList)
print(total)  # Output: 5.7

A More Concise Approach #

You can skip creating the intermediate addList entirely using a generator expression—it's cleaner and more efficient:

eglist = [["a", 1, 2.3],["b",2,3.4]]
total = sum(sublist[-1] for sublist in eglist)
print(total)  # Output: 5.7

This directly iterates over each sublist, grabs its last element, and sums them up in one go.

内容的提问来源于stack exchange，提问作者Nithila Logathas