python - 将 dict 的元组键转换为新的 dict

Question

我有一个像这样的 dict:

{
    ('America', 25, 'm', 'IT'): 10000,
    ('America', 22, 'm', 'IT'): 8999,
    ('Japan',   24, 'f', 'IT'): 9999,
    ('Japan',   23, 'f', 'IT'): 9000
}

现在，在本例中，我想使用键 ('America', 'm', 'IT') 获取所有结果。在上面，那将是:

{25: 10000, 22: 8999}

我目前的解决方案如下:

res = dict()
for key, cnt in stats.items():
    country, age, sex, job = key
    try:
        res[(country, sex, job)][age] = cnt
    except KeyError as e:
        res[(country, sex, job)] = {}
        res[(country, sex, job)][age] = cnt

print res['America', 'm', 'IT']

我有更好的办法吗？因为这段代码看起来并不那么简单。

Answer 1

你可以使用字典推导来做到这一点:

>>> data = {
...     ('America', 25, 'm', 'IT'): 10000,
...     ('America', 22, 'm', 'IT'): 8999,
...     ('Japan',   24, 'f', 'IT'): 9999,
...     ('Japan',   23, 'f', 'IT'): 9000
... }
>>> {x: value for (w, x, y, z), value in data.items() if w == "America" and y == "m" and z == "IT"}
{25: 10000, 22: 8999}