Check if list of objects contain an object with a certain attribute value

问题

I want to check if my list of objects contain an object with a certain attribute value.

class Test:
    def __init__(self, name):
        self.name = name

# in main()
l = []
l.append(Test("t1"))
l.append(Test("t2"))
l.append(Test("t2"))

I want a way of checking if list contains an object with name "t1" for example. How can it be done? I found https://stackoverflow.com/a/598415/292291,

[x for x in myList if x.n == 30]               # list of all matches
any(x.n == 30 for x in myList)                 # if there is any matches
[i for i,x in enumerate(myList) if x.n == 30]  # indices of all matches

def first(iterable, default=None):
    for item in iterable:
        return item
    return default

first(x for x in myList if x.n == 30)          # the first match, if any

I don't want to go through the whole list every time, I just need to know if there's 1 instance which matches. Will first(...) or any(...) or something else do that?

回答1:

As you can easily see from the documentation, the any() function short-circuits an returns True as soon as a match has been found.

any(x.name == "t2" for x in l)

来源：https://stackoverflow.com/questions/9371114/check-if-list-of-objects-contain-an-object-with-a-certain-attribute-value