Python 计算具有匹配属性的对象列表中的元素 [英] Python Count Elements in a List of Objects with Matching Attributes

问题描述

我试图找到一种简单快速的方法来计算列表中符合条件的对象的数量.例如

I am trying to find a simple and fast way of counting the number of Objects in a list that match a criteria. e.g.

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")]

现在计算这个列表中根据属性匹配参数的对象数量的最简单函数是什么?例如，为 Person.Gender == "F" 或 Person.Age <返回 220.

Now what's the simplest function for counting the number of objects in this list that match an argument based on their attributes? E.g., returning 2 for Person.Gender == "F" or Person.Age < 20.

推荐答案

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

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