如何在 Python 中相互比较 2 个列表？

Question

我有以下 2 个列表。

my_values = ['0,78', '0,40', '0,67']

my_list = [
    ['Morocco', 'Meat', '190,00', '0,15'], 
    ['Morocco', 'Meat', '189,90', '0,32'], 
    ['Morocco', 'Meat', '189,38', '0,44'],
    ['Morocco', 'Meat', '188,94', '0,60'],
    ['Morocco', 'Meat', '188,49', '0,78'],
    ['Morocco', 'Meat', '187,99', '0,101'],
    ['Spain', 'Meat', '190,76', '0,10'], 
    ['Spain', 'Meat', '190,16', '0,20'], 
    ['Spain', 'Meat', '189,56', '0,35'],
    ['Spain', 'Meat', '189,01', '0,40'],
    ['Spain', 'Meat', '188,13', '0,75'],
    ['Spain', 'Meat', '187,95', '0,85'],
    ['Italy', 'Meat', '190,20', '0,11'],
    ['Italy', 'Meat', '190,10', '0,31'], 
    ['Italy', 'Meat', '189,32', '0,45'],
    ['Italy', 'Meat', '188,61', '0,67'],
    ['Italy', 'Meat', '188,01', '0,72'],
    ['Italy', 'Meat', '187,36', '0,80']]

现在对每一个列表中my_list我要检查什么index[2]是index[3]相等的值my_values. index[2]是这是第3排my_list，并index[4]在第4行my_list这么短说：

1. 摩洛哥我要检查什么index[2]是index[3]==0,78
2. 对于西班牙我要检查什么index[2]是index[3]==0,40
3. 对于意大利我要检查什么index[2]是index[3]==0,67

这是我试过的代码：

my_answers = []
for key,sublists in itertools.groupby(my_list,lambda y:y[0]): 
    v = min(x for x in sublists if float(x[3].replace(',', '.')) == x for x in my_values); 
    my_answers.append(v[-2])
    
print(my_answers)

这是我收到的：

ValueError: min() arg is an empty sequence

这是我的预期：

188,49
189,01
188,61

Answer 1

这是你想要的吗？

my_values = ['0,78', '0,40', '0,67']

my_list = [
    ['Morocco', 'Meat', '190,00', '0,15'], 
    ['Morocco', 'Meat', '189,90', '0,32'], 
    ['Morocco', 'Meat', '189,38', '0,44'],
    ['Morocco', 'Meat', '188,94', '0,60'],
    ['Morocco', 'Meat', '188,49', '0,78'],
    ['Morocco', 'Meat', '187,99', '0,101'],
    ['Spain', 'Meat', '190,76', '0,10'], 
    ['Spain', 'Meat', '190,16', '0,20'], 
    ['Spain', 'Meat', '189,56', '0,35'],
    ['Spain', 'Meat', '189,01', '0,40'],
    ['Spain', 'Meat', '188,13', '0,75'],
    ['Spain', 'Meat', '187,95', '0,85'],
    ['Italy', 'Meat', '190,20', '0,11'],
    ['Italy', 'Meat', '190,10', '0,31'], 
    ['Italy', 'Meat', '189,32', '0,45'],
    ['Italy', 'Meat', '188,61', '0,67'],
    ['Italy', 'Meat', '188,01', '0,72'],
    ['Italy', 'Meat', '187,36', '0,80'],
]

print("\n".join(i[2] for i in my_list if i[3] in my_values))

输出：

188,49
189,01
188,61

这是单线的作用：

• 在您的列表循环my_list和检查从各子表与索引值[3]反对票的my_value列表
• 如果条件是True，它“保留”索引中的值[2]
• 最后它加入了所有values与上述匹配的，例如189,01
• 顺便说一句，这i[2] for i in my_list if i[3] in my_values是一个发电机
• "\n" 是换行符

编辑：

如果您希望输出在列表中，只需执行以下操作：

yet_another_list = [i[2] for i in my_list if i[3] in my_values]
print(yet_another_list)

这给你：

['188,49', '189,01', '188,61']