✨ rewrite DATETRUNC

[joocer]

def datetrunc_fast(date, unit):
if unit == 'second':
return date.replace(microsecond=0)
elif unit == 'minute':
seconds_per_minute = 60
full_minutes, remainder = divmod((date - datetime.datetime(1970, 1, 1)).total_seconds(), seconds_per_minute)
return date - datetime.timedelta(seconds=remainder)
elif unit == 'hour':
seconds_per_hour = 60 * 60
full_hours, remainder = divmod((date - datetime.datetime(1970, 1, 1)).total_seconds(), seconds_per_hour)
return date - datetime.timedelta(seconds=remainder)
elif unit == 'day':
days_per_day = 1
full_days, remainder = divmod((date - datetime.datetime(1970, 1, 1)).days, days_per_day)
return date - datetime.timedelta(days=remainder)
elif unit == 'week':
days_per_week = 7
full_weeks, remainder = divmod((date - datetime.datetime(1970, 1, 1)).days, days_per_week)
return date - datetime.timedelta(days=remainder)
elif unit == 'month':
full_months, remainder = divmod(12 * (date.year - 1970) + (date.month - 1), 12)
return date.replace(year=date.year - full_months, month=1)
elif unit == 'quarter':
full_quarters, remainder = divmod(4 * (date.year - 1970) + (date.month - 1) // 3, 4)
return date.replace(year=date.year - full_quarters, month=((remainder * 3) % 12) + 1)
elif unit == 'year':
full_years, remainder = divmod(date.year - 1970, 1)
return date.replace(year=date.year - full_years)
else:
raise ValueError("Invalid unit: {}".format(unit))

[joocer]

It's not a common function and isn't a performance concern, but replacing it removes a third-party piece of code and marginally improves performance.

50%   0.8710ms, 95%   1.5160ms, 99%   2.0860ms, 99.99%  42.8863ms,  100000 cycles of first_party
50%   1.3250ms, 95%   2.3880ms, 99%   2.9770ms, 99.99%  47.4730ms,  100000 cycles of third_party