Date and time handling in the __init()__

ab_trader

Could you please advice the way of date & time handling using __init()__. Say I have data feed and want to have the following indicator values along the history:

from the data beginning to 2000/12/31 it should be 1.0
after 2001/01/01 it should be 2.0

I've developed an indicator using next(). It simply compares last data feed dates and dates shown, and set values accordingly . Is there a way to make the same thing in the __init()__? It seems to me that it might be faster.

backtrader

Comparison is implemented for datetime.time instances and lines, but not for datetime.datetime or datetime.date, which forbids a clean implementation of that idea with something like:

def __init__(self):
    self.lines.myline = 1 + (self.data.datetime >= datetime.date(2001, 1, 1))

But there is something which can be done even if not so elegant

def __init__(self):
    self.lines.myline = 1 + (self.data.datetime >= date2num(datetime.date(2001, 1, 1)))

Instead of directly comparing with the datetime.date instance, the comparison is done against the numeric value.

ab_trader

@backtrader Thank you!

I've used bt.date2num() function for transformation. Also I've found out that you rewrote if operator which can be applied to lines. That helped me also.

backtrader

Edited the snippet from above to reflect that the correct usage is with date2num (obviously)

Of course using the If from backtrader allows for much more complex scenarios. The 1 + boolean in the snippet was just meant to solve the hypothetical case presented above (1 until date x, 2 from that point onwards)