如何获取 python 中的字典列表中的键值列表？

Question

我有一个字典列表：

[{"app1": "value1"},{"app2": "value2"},{"app1": "value3"},{"app1": "value4"}, {"app3": "value5"}]

如何获取列表中某个键的所有值？ 因此，例如对于“app1”，它应该变成这样：

{"app1":["value1", "value3", "value4"]}

对于“app2”，它就变成了：

 {"app2":["value2"]}

Answer 1

使用带有嵌套for循环的defaultdict

from collections import defaultdict 

d = defaultdict(list)

lst = [{"app1": "value1"},{"app2": "value2"},{"app1": "value3"},{"app1": "value4"}, {"app3": "value5"}]

for i in lst:
    for k,v in i.items():
        d[k].append(v)

print(dict(d))

{'app1': ['value1', 'value3', 'value4'], 'app2': ['value2'], 'app3': ['value5']}

Answer 2

a = [{"app1": "value1"},{"app2": "value2"},{"app1": "value3"},{"app1": "value4"}, {"app3": "value5"}] #list of dicts

k = "app1" #key to look for

out = {k: []}
for item in a:
    for key in list(item):
        if key == k:
            out[k].append(item[key])

print(out)

{'app1': ['value1', 'value3', 'value4']}

Answer 3

您可以使用列表推导来获取给定键的所有值：

>>> data = [{"app1": "value1"},{"app2": "value2"},{"app1": "value3"},{"app1": "value4"}, {"app3": "value5"}]
>>> {"app1": [d["app1"] for d in data if "app1" in d]}
{'app1': ['value1', 'value3', 'value4']}

如果你想把它全部累积到一个 dict 中，只需将列表理解放入一个 dict 理解中：

>>> {k: [d[k] for d in data if k in d] for d in data for k in d}
{'app1': ['value1', 'value3', 'value4'], 'app2': ['value2'], 'app3': ['value5']}