Python 如何在django中聚合数据？

我有一个模型，它的实例每小时创建一次：

class Entry(models.Model):
    class Meta:
        ordering = ['time']

    time = models.DateTimeField()
    no2 = models.FloatField()
    co = models.FloatField()
    humidity = models.FloatField()
    temperature = models.FloatField()

我想获得上个月天数的平均值，例如，包含每天平均值的30个实例。如何实现？现在我写了这个方法：

def average_for_period(self, start, end):
        entries_for_period = Entry.objects.filter(time__gte=start, time__lte=end)
        average_value = entries_for_period.aggregate(Avg('temperature'), Avg('no2'), Avg('co'), Avg('humidity'))
        return Entry(**average_value)

---

我应该如何实现功能性？

我建议您可以通过作业调度器定期执行一些script.py。py可以像这样在django shell之外处理django项目

import sys, os

PATH_TO_DJANGO = 'path/to/django/project'
sys.path.append(PATH_TO_DJANGO)
os.environ['DJANGO_SETTINGS_MODULE'] = 'project.settings'

from app import Entry # can be imported after the above config...
import average_for_period # your custom function

# do what you want to ...

---

我建议您可以通过作业调度器定期执行一些script.py。py可以像这样在django shell之外处理django项目

import sys, os

PATH_TO_DJANGO = 'path/to/django/project'
sys.path.append(PATH_TO_DJANGO)
os.environ['DJANGO_SETTINGS_MODULE'] = 'project.settings'

from app import Entry # can be imported after the above config...
import average_for_period # your custom function

# do what you want to ...

---

除了返回值之外，您做的一切都是正确的。聚合查询不应是条目实例

avg_values = ['temperature', 'no2', 'co', 'humidity']
average_value = entries_for_period.aggregate(*[Avg(x) for x in avg_values])
return {x:average_value['%s__avg' % x] for x in avg_values}

这将返回类似dict的命令

{'temperature': 202.48803054780439,
 'no2': 4881.734909678366,
 'co': None,
 'humidity': 200}

---

除了返回值之外，您做的一切都是正确的。聚合查询不应是条目实例

avg_values = ['temperature', 'no2', 'co', 'humidity']
average_value = entries_for_period.aggregate(*[Avg(x) for x in avg_values])
return {x:average_value['%s__avg' % x] for x in avg_values}

这将返回类似dict的命令

{'temperature': 202.48803054780439,
 'no2': 4881.734909678366,
 'co': None,
 'humidity': 200}