Python Count Elements in a List of Objects with Matching Attributes

Question

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,         


        

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