如何在groupBy的结果列表中获取distinct值

import java.util.*;
import java.util.stream.Collectors;

public class DistinctValuesExample {
    public static void main(String[] args) {
        List<Person> people = Arrays.asList(
            new Person("Alice", 25),
            new Person("Bob", 30),
            new Person("Alice", 25),
            new Person("Charlie", 35)
        );

        Map<String, List<Person>> peopleByAge = people.stream()
            .collect(Collectors.groupingBy(Person::getAge));

        Map<Integer, Set<String>> distinctNamesByAge = peopleByAge.entrySet().stream()
            .collect(Collectors.toMap(
                Map.Entry::getKey,
                e -> e.getValue().stream()
                    .map(Person::getName)
                    .collect(Collectors.toSet())
            ));

        System.out.println(distinctNamesByAge);
    }
}

class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}

SELECT age, DISTINCT name
FROM people
GROUP BY age;

import pandas as pd

data = {
    'name': ['Alice', 'Bob', 'Alice', 'Charlie'],
    'age': [25, 30, 25, 35]
}

df = pd.DataFrame(data)

distinct_names_by_age = df.groupby('age')['name'].nunique().reset_index()
print(distinct_names_by_age)