How to exclude certain hours between two date differenece?-CodePudding

I want to get the total hours difference between two timestamps but I want to exclude certain hour in there . I want to exclude these hours from 5PM-10AM everyday.

  from datetime import datetime
  def get_total_hours(model_instance):
      datetime = model_instance.datetime
      now = datetime.now()
      diff = now - datetime
      total_secs = diff.total_seconds()
      hours =  total_secs // 3600
      return hours

CodePudding user response：

I'd envision the problem geometrically:

          day n     day n 1   etc...
        _______________________________________________________________________
00:00   |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
EXCLUDED|         |         |         |         |         |-- t2 ---|         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
10:00   |.........|.........|.........|.........|.........|.........|.........|
        |         |xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|         |         |
        |         |xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|         |         |
        |         |xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|         |         |
COUNTED |-- t1 ---|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|         |         |
        |xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|         |         |
        |xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|         |         |
        |xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|xxxxxxxxx|         |         |
17:00   |.........|.........|.........|.........|.........|.........|.........|
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
EXCLUDED|         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
        |         |         |         |         |         |         |         |
23:59   |_________|_________|_________|_________|_________|_________|_________|

Whatever t1 and t2 might be, your answer is the area of a rectangle (height x width) plus some edge case handling at the ends.

CodePudding user response：

First, check the remaining hours for each date.

Then, check the day gap between the start and end dates.

import datetime

dt_start = datetime.datetime(year=2022, month=7, day=31, hour=20)
dt_end = datetime.datetime(year=2022, month=8, day=2, hour=10, minute=30)

dt_start_gap_lb = dt_start.replace(hour=10, minute=0, second=0, microsecond=0)
dt_start_gap_ub = dt_start.replace(hour=17, minute=0, second=0, microsecond=0)
dt_end_gap_lb = dt_end.replace(hour=10, minute=0, second=0, microsecond=0)
dt_end_gap_ub = dt_end.replace(hour=17, minute=0, second=0, microsecond=0)

dt_start_remain = dt_start_gap_ub - max(dt_start_gap_lb, dt_start)
dt_end_remain = min(dt_end_gap_ub, dt_end) - dt_end_gap_lb

dt_start_remain_hours = 0 if dt_start_remain.days < 0 else dt_start_remain.seconds / 3600.0
dt_end_remain_hours = 0 if dt_end_remain.days < 0 else dt_end_remain.seconds / 3600.0

gap_hours = max((dt_end_gap_lb - dt_start_gap_ub).days * (17-10)   dt_start_remain_hours   dt_end_remain_hours, 0)

Results:

dt_start = datetime.datetime(year=2022, month=7, day=31, hour=20)
dt_end = datetime.datetime(year=2022, month=8, day=2, hour=10, minute=30)
> 7.5

dt_start = datetime.datetime(year=2022, month=7, day=31, hour=16, minute=30)
dt_end = datetime.datetime(year=2022, month=8, day=2, hour=10, minute=30)
> 8.0

dt_start = datetime.datetime(year=2022, month=7, day=31, hour=5, minute= 30)
dt_end = datetime.datetime(year=2022, month=7, day=31, hour=10, minute=30)
> 0.5

CodePudding user response：

Given a model Foo with a field timestamp, and t1 and t2 defined as per the question:

Foo.objects.filter(timestamp__gte=t1, timestamp__lte=t2
   ).exclude( timestamp__hour__gte=17 # up to 23 by definition
   ).exclude( timestamp__hour__lte=9  # down to 0 by definition
   )

Alternatively,

    .exclude( timestamp__hour__in=[
        0,1,2,3,4,5,6,7,8,9,17,18,19,20,21,22,23 ])