我怎样才能对 if/elif 进行理解，而不是其他？

Question

I want to create a comprehension for from this:

for w in s:
    if w in pw_set:
        a[w] += 1
    elif t in nw_set:
        a[w] += 1

I have something like this but it doesn't work

[(a[w]+=1) if (w in pw_set) else (a[w]+=1) if (w in nw_set) for w in s]

Answer 1

If you really, absolutely want to do that with a list comprehension, you'll need a collections.Counter to accumulate the results into. (It can count occurrences from a flat list of values.)

> pw_set = {'a','b', 'c'}
> nw_set = {}
> s = ['a', 'b', 'q', 'z', 'e']
> a = collections.Counter(
    [
        w
        for w in (
            w if (w in pw_set or w in nw_set) else None
            for w in s
        )
        if w is not None
    ]
)
Counter({'a': 1, 'b': 1})