我可以用更好的方式编写简单的 Python 代码吗？

Question

I should rewrite my own function in a better way. The function takes an iterator and a sequence of boolean functions and returns an iterator of the elements in the input iterator which returns a truthy value.

def allTrue (iterator, funz):
for i in iterator:
    count = 0
    for f in funz:
        if f(i):
            count = count+1
        if count==len(funz):
            yield i

I tried to write this:

def allTrue2 (iterator, funz):
    return (filter (f , iterator) for f in funz)

But it's wrong. How could I improve the code?

Output:

print(list(allTrue(range(50),
               (lambda x: x % 3 == 0,
                lambda x: x > 10,
                lambda x: x < 44)
               )))

>>> [12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42]

Answer 1

And if you want a one-liner, just for completeness:

def allTrue (iterator, funz):
    return (i for i in iterator if all(f(i) for f in funz))

Note that this returns a generator, so it has the same effect as using yield .

Answer 2

def allTrue(iterator, funz):
    for i in iterator:
        if all(f(i) for f in funz):
            yield i

Answer 3

You can yield from a generator expression like this:

def allTrue(iterator, funz):
    yield from (i for i in iterator if all(f(i) for f in funz))

Answer 4

Keeping things close to your initial approach, you might use a for/else to break once a function returns False and move on to the next element. Only if all functions returned True and the loop never broke, the else part will be executed and yield this result:

def allTrue (iterator, funz):
    for i in iterator:
        for f in funz:
            if not f(i):
                break
        else:
            yield i

---

Regarding your filter approach, you basically created an iterator of iterators. You have an iterator filtering the list according to each function separatly . You want to filter the list, returning a single iterator, with the condition that all functions return True :

def allTrue2 (iterator, funz):
    return filter(lambda i: all(f(i) for f in funz), iterator)