python - 计算 python 列表中对象的出现次数

Question

假设我有以下列表:

result = [{"name": "a", "number": 1},
{"name": "a", "number": 2},
{"name": "b", "number": 1},
{"name": "a", "number": 1}]

我可以把它变成这样的吗:

result = [{"name": "a", "number": 1, "count": 2},
{"name": "a", "number": 2},
{"name": "b", "number": 1}]

我尝试使用 Count 类，但无法使其与字典一起使用。

Answer 1

您可以将 collections.Counter 与列表理解一起使用:

from collections import Counter
[dict(tuple(t) + (('count', c),)) for t, c in Counter(frozenset(d.items()) for d in result).items()]

返回:

[{'number': 1, 'name': 'a', 'count': 2}, {'number': 2, 'name': 'a', 'count': 1}, {'number': 1, 'name': 'b', 'count': 1}]