如何对random.choices选取内容求和？歌曲列表时长求和求助

错误原因 #

1. 未定义变量time：你的代码中使用了time变量，但从未对其赋值，应该从已有的my_favorite_songs列表中提取数据。
2. 直接对列表求和无效：即便你替换变量为my_favorite_songs，random.choices返回的是3个包含歌曲名和时长的子列表，sum()函数无法直接对列表类型的元素求和，必须提取子列表中的时长数值。

修复后的代码示例 #

方法一：先提取时长列表再随机选择 #

import random

my_favorite_songs = [
    ['Waste a Moment', 3.03],
    ['New Salvation', 4.02],
    ['Staying\' Alive', 3.40],
    ['Out of Touch', 3.03],
    ['A Sorta Fairytale', 5.28],
    ['Easy', 4.15],
    ['Beautiful Day', 4.04],
    ['Nowhere to Run', 2.58],
    ['In This World', 4.02],
]

# 提取所有歌曲的时长到单独列表
song_durations = [song[1] for song in my_favorite_songs]
# 随机选3个时长并求和
total_duration = sum(random.choices(song_durations, k=3))
print(total_duration)

方法二：先选歌曲再提取时长求和 #

import random

my_favorite_songs = [
    ['Waste a Moment', 3.03],
    ['New Salvation', 4.02],
    ['Staying\' Alive', 3.40],
    ['Out of Touch', 3.03],
    ['A Sorta Fairytale', 5.28],
    ['Easy', 4.15],
    ['Beautiful Day', 4.04],
    ['Nowhere to Run', 2.58],
    ['In This World', 4.02],
]

# 随机选取3首歌曲
selected_songs = random.choices(my_favorite_songs, k=3)
# 提取每首歌的时长并求和
total_duration = sum(song[1] for song in selected_songs)
print(total_duration)

内容的提问来源于stack exchange，提问作者rrenyaa