python - 比较两个 collections.defaultdict 并删除相似的值

Question

我有两个 collections.defaultdict并尝试从 d1 中删除值也在 d2 .

from collections import Counter, defaultdict
d1 = Counter({'hi': 22, 'bye': 55, 'ok': 33})
d2 = Counter({'hi': 10, 'hello': 233, 'nvm': 96})

理想结果:

d3 = set()
d3 = ({'bye':55, 'ok':33})

到目前为止，我已经尝试过:

d3 = set()
d3 = d1 - d2
print(d3)
Counter({'bye': 55, 'ok': 33, 'hi': 12}) 

但这保持与 'hi' 相同的值即使我想删除所有类似的。

Answer 1

从，d1和 d2是 Counter它们实现与集合不同的减法的对象。

From collections.Counter(emphasis mine):

Addition and subtraction combine counters by adding or subtracting the counts of corresponding elements.

From set.difference or set - other:

Return a new set with elements in the set that are not in the others.

也就是说，您可以使用 Counter.keys并使用 difference就像套。

keys = d1.keys() - d2.keys()
# keys = {'bye', 'ok'}

out = {k: d1[k] for k in keys}
# out = {'bye': 55, 'ok': 33}