将Django TimeField中的时间乘以float [英] Multiply time in Django TimeField by float

问题描述

我正在尝试将当前表示为字符串的时间读入Python 2.7的Django TimeField模型中，并同时通过float对其进行缩放.

I'm trying to read a time currently represented as a string into a Django TimeField Model in Python 2.7 and scale it via a float at the same time.

例如:

00:31:14 / 1.0617 = 00:29:20

我已经成功读取了时间并将其存储到模型中，但是无法以很好"的方式缩放时间(当前，我从数据库中读取了时间对象并进行了更新).

I've successfully read in the time and stored into the model but can't scale the time in a "nice" way (currently I read the time object back out of the database and update it).

在保存到数据库之前，我想使用TimeField所基于的python datatime对象进行此计算.

I would like to use the python datatime object that the TimeField is based on to do this calculation before saving to the database.

相关代码:

class Time(models.Model):
    time = models.TimeField()
    date = models.DateField()

date = "12/6/2009"
time = "00:31:14"
date = datetime.strptime(date, "%d/%m/%Y").strftime("%Y-%m-%d")
time = models.Time(date=date, time=time)
time.save()

db_instance = models.Time.objects.all().filter(id=time.id)[0]

db_instance.time = db_instance.time.replace(
    minute=int((db_instance.time.minute * 60 + db_instance.time.second) / 1.0617) / 60,
    second=int((db_instance.time.minute * 60 + db_instance.time.second) / 1.0617) % 60)

更新

如Dandekar所建议，我将timedelta类扩展为包括乘法和除法:

As suggested by Dandekar I've extended the timedelta class to include multiplication and division:

from datetime import timedelta

class TimeDeltaExtended(timedelta):
    def __div__(self, divisor):
        return TimeDeltaExtended(seconds=self.total_seconds()/divisor)

    def __mul__(self, multiplier):
        return TimeDeltaExtended(seconds=self.total_seconds()*multiplier)

推荐答案

按浮点数除法在Python 2.x中不起作用，但在python 3.2x中起作用因此，通常来说，要减去时间，您需要执行以下操作:

Division by float does not work in Python 2.x but works in python 3.2x So normally, to SUBTRACT time, you do something like below:

dt = date+" "+time
dt=datetime.datetime.strptime(dt, "%d/%m/%Y %H:%M:%S")
delta=datetime.timedelta(seconds=1.0617)
adjusted=dt-delta
print adjusted.strftime("%d/%m/%Y %H:%M:%S")

要划分时间，您必须将timedelta子类化为类似的

To DIVIDE time, you would have to subclass timedelta to something like

class MyTimeDelta(timedelta):
    def __div__(self, deltafloat):
        # Code

有关的更多信息此处.希望有帮助.

More on that here. Hope that helps.

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