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from agate.aggregations.base import Aggregation
from agate.data_types import Date, DateTime, Number, TimeDelta
from agate.exceptions import DataTypeError
class Max(Aggregation):
"""
Find the maximum value in a column.
This aggregation can be applied to columns containing :class:`.Date`,
:class:`.DateTime`, or :class:`.Number` data.
:param column_name:
The name of the column to be searched.
"""
def __init__(self, column_name):
self._column_name = column_name
def get_aggregate_data_type(self, table):
column = table.columns[self._column_name]
if isinstance(column.data_type, (Date, DateTime, Number, TimeDelta)):
return column.data_type
def validate(self, table):
column = table.columns[self._column_name]
if not isinstance(column.data_type, (Date, DateTime, Number, TimeDelta)):
raise DataTypeError('Min can only be applied to columns containing DateTime, Date or Number data.')
def run(self, table):
column = table.columns[self._column_name]
data = column.values_without_nulls()
if data:
return max(data)
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