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#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import itertools
__all__ = ['ParamGridBuilder']
class ParamGridBuilder(object):
"""
Builder for a param grid used in grid search-based model selection.
>>> from classification import LogisticRegression
>>> lr = LogisticRegression()
>>> output = ParamGridBuilder().baseOn({lr.labelCol: 'l'}) \
.baseOn([lr.predictionCol, 'p']) \
.addGrid(lr.regParam, [1.0, 2.0, 3.0]) \
.addGrid(lr.maxIter, [1, 5]) \
.addGrid(lr.featuresCol, ['f']) \
.build()
>>> expected = [ \
{lr.regParam: 1.0, lr.featuresCol: 'f', lr.maxIter: 1, lr.labelCol: 'l', lr.predictionCol: 'p'}, \
{lr.regParam: 2.0, lr.featuresCol: 'f', lr.maxIter: 1, lr.labelCol: 'l', lr.predictionCol: 'p'}, \
{lr.regParam: 3.0, lr.featuresCol: 'f', lr.maxIter: 1, lr.labelCol: 'l', lr.predictionCol: 'p'}, \
{lr.regParam: 1.0, lr.featuresCol: 'f', lr.maxIter: 5, lr.labelCol: 'l', lr.predictionCol: 'p'}, \
{lr.regParam: 2.0, lr.featuresCol: 'f', lr.maxIter: 5, lr.labelCol: 'l', lr.predictionCol: 'p'}, \
{lr.regParam: 3.0, lr.featuresCol: 'f', lr.maxIter: 5, lr.labelCol: 'l', lr.predictionCol: 'p'}]
>>> len(output) == len(expected)
True
>>> all([m in expected for m in output])
True
"""
def __init__(self):
self._param_grid = {}
def addGrid(self, param, values):
"""
Sets the given parameters in this grid to fixed values.
"""
self._param_grid[param] = values
return self
def baseOn(self, *args):
"""
Sets the given parameters in this grid to fixed values.
Accepts either a parameter dictionary or a list of (parameter, value) pairs.
"""
if isinstance(args[0], dict):
self.baseOn(*args[0].items())
else:
for (param, value) in args:
self.addGrid(param, [value])
return self
def build(self):
"""
Builds and returns all combinations of parameters specified
by the param grid.
"""
keys = self._param_grid.keys()
grid_values = self._param_grid.values()
return [dict(zip(keys, prod)) for prod in itertools.product(*grid_values)]
if __name__ == "__main__":
import doctest
doctest.testmod()
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