Question

我有一个数据示例列表：

<a href="jeans1-big.jpg" class="MagicZoom" id="jeans"><img src="jeans1-small.jpg" /></a>

<a data-zoom-id="jeans" href="jeans1-big.jpg" data-image="jeans1-small.jpg"><img src="jeans1-tiny.jpg" /></a>
<a data-zoom-id="jeans" href="jeans2-big.jpg" data-image="jeans2-small.jpg"><img src="jeans2-tiny.jpg" /></a>
<a data-zoom-id="jeans" href="jeans3-big.jpg" data-image="jeans3-small.jpg"><img src="jeans3-tiny.jpg" /></a>
<a data-zoom-id="jeans" href="jeans4-big.jpg" data-image="jeans4-small.jpg"><img src="jeans4-tiny.jpg" /></a>
<a data-zoom-id="jeans" href="jeans5-big.jpg" data-image="jeans5-small.jpg"><img src="jeans5-tiny.jpg" /></a>

我想做的是循环上面的数据并创建一个字典数据结构，我试图创建的一个例子是：

res = { 'results': [
{'consumption': 0.025, 'interval_start': '2021-06-27T00:00:00+01:00', 'interval_end': '2021-06-27T00:30:00+01:00'},
{'consumption': 0.043, 'interval_start': '2021-06-26T23:30:00+01:00', 'interval_end': '2021-06-27T00:00:00+01:00'},
{'consumption': 0.053, 'interval_start': '2021-06-26T23:00:00+01:00', 'interval_end': '2021-06-26T23:30:00+01:00'},
{'consumption': 0.056, 'interval_start': '2021-06-26T22:30:00+01:00', 'interval_end': '2021-06-26T23:00:00+01:00'},
{'consumption': 0.031, 'interval_start': '2021-06-26T22:00:00+01:00', 'interval_end': '2021-06-26T22:30:00+01:00'},
{'consumption': 0.129, 'interval_start': '2021-06-26T21:30:00+01:00', 'interval_end': '2021-06-26T22:00:00+01:00'},
{'consumption': 0.19,  'interval_start': '2021-06-26T21:00:00+01:00', 'interval_end': '2021-06-26T21:30:00+01:00'},
{'consumption': 0.164, 'interval_start': '2021-06-26T20:30:00+01:00', 'interval_end': '2021-06-26T21:00:00+01:00'},
{'consumption': 0.145, 'interval_start': '2021-06-26T20:00:00+01:00', 'interval_end': '2021-06-26T20:30:00+01:00'},
{'consumption': 0.213, 'interval_start': '2021-06-26T19:30:00+01:00', 'interval_end': '2021-06-26T20:00:00+01:00'},
{'consumption': 0.167, 'interval_start': '2021-06-26T19:00:00+01:00', 'interval_end': '2021-06-26T19:30:00+01:00'},
{'consumption': 0.333, 'interval_start': '2021-06-26T18:30:00+01:00', 'interval_end': '2021-06-26T19:00:00+01:00'},
{'consumption': 0.133, 'interval_start': '2021-06-26T18:00:00+01:00', 'interval_end': '2021-06-26T18:30:00+01:00'},
{'consumption': 0.211, 'interval_start': '2021-06-26T17:30:00+01:00', 'interval_end': '2021-06-26T18:00:00+01:00'},
{'consumption': 0.135, 'interval_start': '2021-06-26T17:00:00+01:00', 'interval_end': '2021-06-26T17:30:00+01:00'},
{'consumption': 0.158, 'interval_start': '2021-06-26T16:30:00+01:00', 'interval_end': '2021-06-26T17:00:00+01:00'},
{'consumption': 0.073, 'interval_start': '2021-06-26T16:00:00+01:00', 'interval_end': '2021-06-26T16:30:00+01:00'},
{'consumption': 0.077, 'interval_start': '2021-06-26T15:30:00+01:00', 'interval_end': '2021-06-26T16:00:00+01:00'},
{'consumption': 0.125, 'interval_start': '2021-06-26T15:00:00+01:00', 'interval_end': '2021-06-26T15:30:00+01:00'},
{'consumption': 0.201, 'interval_start': '2021-06-26T14:30:00+01:00', 'interval_end': '2021-06-26T15:00:00+01:00'},
{'consumption': 0.043, 'interval_start': '2021-06-26T14:00:00+01:00', 'interval_end': '2021-06-26T14:30:00+01:00'},
] }

我为此编写的代码是：

{
  "2021": {
    "06": {
      "01": [
        {
          "interval_start": "23:00",
          "interval_end": "23:30",
          "consumption": "0.021"
        },
        {
          "interval_start": "22:30",
          "interval_end": "23:00",
          "consumption": "0.021"
        }
      ],
      "02": [
        {
          "interval_start": "23:00",
          "interval_end": "23:30",
          "consumption": "0.021"
        },
        {
          "interval_start": "22:30",
          "interval_end": "23:00",
          "consumption": "0.021"
        }
      ]
    }
  }
}

其中 main_obj = {} for i in res['results']: date = i["interval_start"].split("T")[0].split("-") insert_obj = { "interval_start" : i['interval_start'], "interval_end": i["interval_end"], "consumption": i["consumption"] } main_obj[date[0]] = {} main_obj[date[0]][date[1]] = {} main_obj[date[0]][date[1]][date[2]] = [] main_obj[date[0]][date[1]][date[2]].append(insert_obj) print(main_obj) 是上面的 Dicts 列表。当我打印出来时，我得到：

res['results']

我遇到的问题是为什么当我遍历每个 dict 时，它没有被添加到列表 { '2021': { '06': { '26': [{ 'interval_start': '2021-06-26T14:00:00+01:00', 'interval_end': '2021-06-26T14:30:00+01:00', 'consumption': 0.043 }] } } } 中？另外，由于 dicts 具有唯一键，为什么我只看到 26 而不是 27 的插入？哪个在索引 0 处？

任何帮助都会受到赞赏，因为我已经为此挠头一段时间了！

Answer 1

您正在使用 main_obj[date[0]] = {} 之类的无条件赋值覆盖任何现有的字典/列表；如果已经看到 date[0]，则您正在擦除之前存在的所有数据。

改用 setdefault 方法。（我不确定 PEP-8 批准的分线是什么样的。）

(main_obj
  .setdefault(date[0], {})
  .setdefault(date[1], {})
  .setdefault(date[2], [])
).append(insert_obj)

Answer 2

正如@chepner 所说，这里的问题是，在循环的每次迭代中，如果存在与该键关联的现有值，您将覆盖与某个字典键关联的现有值。

这是一个时髦的解决方案，使用 functools.partial 和 collections.defaultdict 而不是常规字典的 setdefault 方法。

from collections import defaultdict
from functools import partial
from pprint import pprint

results_list = [
    {'consumption': 0.025, 'interval_start': '2021-06-27T00:00:00+01:00', 'interval_end': '2021-06-27T00:30:00+01:00'},
    {'consumption': 0.043, 'interval_start': '2021-06-26T23:30:00+01:00', 'interval_end': '2021-06-27T00:00:00+01:00'},
    {'consumption': 0.053, 'interval_start': '2021-06-26T23:00:00+01:00', 'interval_end': '2021-06-26T23:30:00+01:00'},
    {'consumption': 0.056, 'interval_start': '2021-06-26T22:30:00+01:00', 'interval_end': '2021-06-26T23:00:00+01:00'},
    {'consumption': 0.031, 'interval_start': '2021-06-26T22:00:00+01:00', 'interval_end': '2021-06-26T22:30:00+01:00'},
    {'consumption': 0.129, 'interval_start': '2021-06-26T21:30:00+01:00', 'interval_end': '2021-06-26T22:00:00+01:00'},
    {'consumption': 0.19, 'interval_start': '2021-06-26T21:00:00+01:00', 'interval_end': '2021-06-26T21:30:00+01:00'},
    {'consumption': 0.164, 'interval_start': '2021-06-26T20:30:00+01:00', 'interval_end': '2021-06-26T21:00:00+01:00'},
    {'consumption': 0.145, 'interval_start': '2021-06-26T20:00:00+01:00', 'interval_end': '2021-06-26T20:30:00+01:00'},
    {'consumption': 0.213, 'interval_start': '2021-06-26T19:30:00+01:00', 'interval_end': '2021-06-26T20:00:00+01:00'},
    {'consumption': 0.167, 'interval_start': '2021-06-26T19:00:00+01:00', 'interval_end': '2021-06-26T19:30:00+01:00'},
    {'consumption': 0.333, 'interval_start': '2021-06-26T18:30:00+01:00', 'interval_end': '2021-06-26T19:00:00+01:00'},
    {'consumption': 0.133, 'interval_start': '2021-06-26T18:00:00+01:00', 'interval_end': '2021-06-26T18:30:00+01:00'},
    {'consumption': 0.211, 'interval_start': '2021-06-26T17:30:00+01:00', 'interval_end': '2021-06-26T18:00:00+01:00'},
    {'consumption': 0.135, 'interval_start': '2021-06-26T17:00:00+01:00', 'interval_end': '2021-06-26T17:30:00+01:00'},
    {'consumption': 0.158, 'interval_start': '2021-06-26T16:30:00+01:00', 'interval_end': '2021-06-26T17:00:00+01:00'},
    {'consumption': 0.073, 'interval_start': '2021-06-26T16:00:00+01:00', 'interval_end': '2021-06-26T16:30:00+01:00'},
    {'consumption': 0.077, 'interval_start': '2021-06-26T15:30:00+01:00', 'interval_end': '2021-06-26T16:00:00+01:00'},
    {'consumption': 0.125, 'interval_start': '2021-06-26T15:00:00+01:00', 'interval_end': '2021-06-26T15:30:00+01:00'},
    {'consumption': 0.201, 'interval_start': '2021-06-26T14:30:00+01:00', 'interval_end': '2021-06-26T15:00:00+01:00'},
    {'consumption': 0.043, 'interval_start': '2021-06-26T14:00:00+01:00', 'interval_end': '2021-06-26T14:30:00+01:00'},
]

main_obj = defaultdict(partial(defaultdict, partial(defaultdict, list)))

for i in results_list:    
    
    date = i["interval_start"].split("T")[0].split("-")    
    
    insert_obj = {
        "interval_start" : i['interval_start'],
        "interval_end": i["interval_end"],
        "consumption": i["consumption"]
        
    }

    main_obj[date[0]][date[1]][date[2]].append(insert_obj)

pprint(main_obj)  # Expected result (I think!)

defaultdict 的文档是 here，您可以在此处阅读有关其工作原理的更多信息：https://stackoverflow.com/a/5900634/13990016。实例化 defaultdict 时，传递给创建默认值的函数必须采用 0 个参数，因此有必要使用 functools.partial 修改此处的函数，以便它们采用的参数比通常更少。 functools.partial 的文档是 here，您可以在此处阅读有关它如何工作的更多信息：How does functools partial do what it does?。

循环尝试创建字典的列表

2 个答案: