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from agate.aggregations.base import Aggregation
class Summary(Aggregation):
"""
Apply an arbitrary function to a column.
:param column_name:
The name of a column to be summarized.
:param data_type:
The return type of this aggregation.
:param func:
A function which will be passed the column for processing.
:param cast:
If :code:`True`, each return value will be cast to the specified
:code:`data_type` to ensure it is valid. Only disable this if you are
certain your summary always returns the correct type.
"""
def __init__(self, column_name, data_type, func, cast=True):
self._column_name = column_name
self._data_type = data_type
self._func = func
self._cast = cast
def get_aggregate_data_type(self, table):
return self._data_type
def run(self, table):
v = self._func(table.columns[self._column_name])
if self._cast:
v = self._data_type.cast(v)
return v
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