IRC-SPHERE/HyperStream

# The MIT License (MIT) # Copyright (c) 2014-2017 University of Bristol
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from hyperstream.tool import AggregateTool

import itertools
from copy import deepcopy


class AggregatePlate(AggregateTool):
    """
    This tool aggregates over a given plate, for example, if the input is all the streams in a node on plate A.B,
    and the aggregation is over plate B, the results will live on plate A alone.
    This can also be thought of as marginalising one dimension of a tensor over the plates.
    This version differs from Aggregate in that the timestamps are maintained, and the meta data is put into the value
    """
    def __init__(self, aggregation_meta_data):
        super(AggregatePlate, self).__init__(aggregation_meta_data=aggregation_meta_data)

    def _execute(self, sources, alignment_stream, interval):
        # Combine the data, apply the mapping and sort (inefficient!)
        return sorted(itertools.chain(*(map(lambda x: self.mapper(source.stream_id.meta_data, x),
                                            source.window(interval, force_calculation=True)) for source in sources)),
                      key=lambda x: x.timestamp)

    def mapper(self, meta_data, instance):
        """
        Pull out the meta data plate value and put it into the instance value
        :param meta_data: the original meta data
        :param instance: the original instance
        :return: the modified instance
        """
        d = dict(meta_data)
        v = d.pop(self.aggregation_meta_data)
        instance = deepcopy(instance)
        instance.value[self.aggregation_meta_data] = v
        return instance