otp.Source.where#

Source.where(condition, discard_on_match=False, stop_on_first_mismatch=False)#

Filter ticks that meet the condition.

Returns new object, original source object is not modified.

Parameters

condition (Operation, eval()) – Condition expression to filter ticks or object evaluating another query. In the latter case another query should have only one tick as a result with only one field.
discard_on_match (bool) –
Inverts the condition.

Ticks that don’t meet the condition will be returned.
stop_on_first_mismatch (bool) – If set, no ticks will be propagated starting with the first tick that does not meet the condition.

Return type

onetick.py.core.source.Source

Examples

Filtering based on expression:

>>> data = otp.Ticks(X=[1, 2, 3, 4])
>>> data = data.where(data['X'] % 2 == 1)
>>> otp.run(data)
                     Time  X
0 2003-12-01 00:00:00.000  1
1 2003-12-01 00:00:00.002  3

Filtering based on the result of another query:

>>> another_query = otp.Tick(WHERE='mod(X, 2) = 1')
>>> data = otp.Ticks(X=[1, 2, 3, 4])
>>> data = data.where(otp.eval(another_query))
>>> otp.run(data)
                     Time  X
0 2003-12-01 00:00:00.000  1
1 2003-12-01 00:00:00.002  3

Using discard_on_match parameter to invert the condition:

>>> data = otp.Ticks(X=[1, 2, 3, 4])
>>> data = data.where(data['X'] % 2 == 1, discard_on_match=True)
>>> otp.run(data)
                     Time  X
0 2003-12-01 00:00:00.001  2
1 2003-12-01 00:00:00.003  4

Using stop_on_first_mismatch parameter to not propagate ticks after first mismatch:

>>> data = otp.Ticks(X=[1, 2, 3, 4])
>>> data = data.where(data['X'] % 2 == 1, stop_on_first_mismatch=True)
>>> otp.run(data)
        Time  X
0 2003-12-01  1