Python 计算具有匹配属性的对象列表中的元素

Question

我正在尝试找到一种简单快速的方法来计算列表中符合条件的对象数量。 例如

class Person:
    def __init__(self, Name, Age, Gender):
        self.Name = Name
        self.Age = Age
        self.Gender = Gender

# List of People
PeopleList = [Person("Joan", 15, "F"), 
              Person("Henry", 18, "M"), 
              Person("Marg", 21, "F")]

现在，根据属性计算列表中与参数匹配的对象数量的最简单函数是什么？ 例如，为 Person.Gender == "F"或 Person.Age < 20 返回 2。

Answer 1

class Person:
    def __init__(self, Name, Age, Gender):
        self.Name = Name
        self.Age = Age
        self.Gender = Gender


>>> PeopleList = [Person("Joan", 15, "F"), 
              Person("Henry", 18, "M"), 
              Person("Marg", 21, "F")]
>>> sum(p.Gender == "F" for p in PeopleList)
2
>>> sum(p.Age < 20 for p in PeopleList)
2