[英]How to sort a list of dict based on their datetime in Python
我有以下清單:
[
{
"attributes":
[
{
"label": "Event Date",
"value": "Tue, 29 Jun 2021 18:30:00 GMT"
}
],
"event": "DT2"
},
{
"attributes":
[
{
"label": "DT3",
"value": true
},
{
"label": "Event Date",
"value": "Thu, 22 Jul 2021 18:30:00 GMT"
}
],
"event": "DT5"
},
{
"attributes": [
{
"label": "DT6",
"value": 1.0
},
{
"label": "Event Date",
"value": "Thu, 08 Jul 2021 18:30:00 GMT"
}
],
"event": "DT7"
}
]
以上數據是dict
的list
。 每個dict
都有一個attributes
list
。 attriutes
又是一個字典,它有很多項目和Event Date
。 我必須根據Event Date
升序對列表中的所有字典進行排序。 我們怎樣才能做到這一點?
您需要先獲取日期時間字符串,然后格式化日期時間字符串:
import datetime
lst = [
{
"attributes":
[
{
"label": "Event Date",
"value": "Tue, 29 Jun 2021 18:30:00 GMT"
}
],
"event": "DT2"
},
{
"attributes":
[
{
"label": "DT3",
"value": True
},
{
"label": "Event Date",
"value": "Thu, 22 Jul 2021 18:30:00 GMT"
}
],
"event": "DT5"
},
{
"attributes": [
{
"label": "DT6",
"value": 1.0
},
{
"label": "Event Date",
"value": "Thu, 08 Jul 2021 18:30:00 GMT"
}
],
"event": "DT7"
}
]
lst.sort(key=lambda x: datetime.datetime.strptime(next(attr["value"] for attr in x["attributes"] if attr["label"] == "Event Date"), "%a, %d %b %Y %X %Z"))
或更易讀的方式:
def check(x):
for attr in x["attributes"]:
if attr["label"] == "Event Date":
return datetime.datetime.strptime(attr["value"], "%a, %d %b %Y %X %Z")
lst.sort(key=check)
並給了我:
[{'attributes': [{'label': 'Event Date',
'value': 'Tue, 29 Jun 2021 18:30:00 GMT'}],
'event': 'DT2'},
{'attributes': [{'label': 'DT6', 'value': 1.0},
{'label': 'Event Date', 'value': 'Thu, 08 Jul 2021 18:30:00 GMT'}],
'event': 'DT7'},
{'attributes': [{'label': 'DT3', 'value': True},
{'label': 'Event Date', 'value': 'Thu, 22 Jul 2021 18:30:00 GMT'}],
'event': 'DT5'}]
您想按鍵排序。
對於更簡單的示例,您將如何執行此操作:
my_list = [
{
"foo": 5,
"bar": 4,
},
{
"foo": 3,
"bar": 2,
},
{
"foo": 1,
"bar": 0,
},
]
# This will sort the list according to the "foo" in each dictionary.
my_list.sort(key=lambda dictionary: dictionary["foo"])
對於您的特定情況,由於它更復雜,我將創建一個函數而不是使用 lambda 表達式。 此外,我將使用datetime
來幫助我比較日期字符串。
from datetime import datetime
def key_function(dictionary):
attributes = dictionary["attributes"]
for attribute in attributes:
if attribute["label"] == "Event Date":
date_string = attribute["value"]
date = datetime.strptime(date_string, "%a, %d %b %Y %X %Z")
# Compare dates according to their POSIX timestamp
# I am assuming the dates will be after 1970
return date.timestamp()
raise ValueError("Event Date attribute wasn't found")
my_list.sort(key=key_function)
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