Operator DeltaFilter

Toolkits > com.ibm.streamsx.topology.pysamples 1.1.0 > com.ibm.streamsx.topology.pysamples.kwargs > DeltaFilter

Drops any tuple that is within a delta of the last tuple for the attribute named value.

Python

@spl.map()
class DeltaFilter(object):
    "Drops any tuple that is within a delta of the last tuple for the attribute named `value`."
    def __init__(self, delta):
        self.delta = delta
        self.empty = ()
        self.last_value = None

    # Signature has **kwargs parameter which fixes the
    # SPL tuple parameter passing style to be dictionary
    def __call__(self, **tuple_):
        value = tuple_['value']
        if self.last_value is not None:
            if abs(value - self.last_value) <= self.delta:
                self.last_value = value
                return None
        self.last_value = value
        # Empty tuple will cause any matching input attributes
        # to be carried across to the output tuple
        return self.empty