Source code for pyspark.ml.param
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# 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,
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from abc import ABCMeta
import copy
from pyspark import since
from pyspark.ml.util import Identifiable
__all__ = ['Param', 'Params']
[docs]class Param(object):
"""
A param with self-contained documentation.
.. versionadded:: 1.3.0
"""
def __init__(self, parent, name, doc):
if not isinstance(parent, Identifiable):
raise TypeError("Parent must be an Identifiable but got type %s." % type(parent))
self.parent = parent.uid
self.name = str(name)
self.doc = str(doc)
def __str__(self):
return str(self.parent) + "__" + self.name
def __repr__(self):
return "Param(parent=%r, name=%r, doc=%r)" % (self.parent, self.name, self.doc)
def __hash__(self):
return hash(str(self))
def __eq__(self, other):
if isinstance(other, Param):
return self.parent == other.parent and self.name == other.name
else:
return False
[docs]class Params(Identifiable):
"""
Components that take parameters. This also provides an internal
param map to store parameter values attached to the instance.
.. versionadded:: 1.3.0
"""
__metaclass__ = ABCMeta
def __init__(self):
super(Params, self).__init__()
#: internal param map for user-supplied values param map
self._paramMap = {}
#: internal param map for default values
self._defaultParamMap = {}
#: value returned by :py:func:`params`
self._params = None
@property
@since("1.3.0")
[docs] def params(self):
"""
Returns all params ordered by name. The default implementation
uses :py:func:`dir` to get all attributes of type
:py:class:`Param`.
"""
if self._params is None:
self._params = list(filter(lambda attr: isinstance(attr, Param),
[getattr(self, x) for x in dir(self) if x != "params"]))
return self._params
@since("1.4.0")
[docs] def explainParam(self, param):
"""
Explains a single param and returns its name, doc, and optional
default value and user-supplied value in a string.
"""
param = self._resolveParam(param)
values = []
if self.isDefined(param):
if param in self._defaultParamMap:
values.append("default: %s" % self._defaultParamMap[param])
if param in self._paramMap:
values.append("current: %s" % self._paramMap[param])
else:
values.append("undefined")
valueStr = "(" + ", ".join(values) + ")"
return "%s: %s %s" % (param.name, param.doc, valueStr)
@since("1.4.0")
[docs] def explainParams(self):
"""
Returns the documentation of all params with their optionally
default values and user-supplied values.
"""
return "\n".join([self.explainParam(param) for param in self.params])
@since("1.4.0")
[docs] def getParam(self, paramName):
"""
Gets a param by its name.
"""
param = getattr(self, paramName)
if isinstance(param, Param):
return param
else:
raise ValueError("Cannot find param with name %s." % paramName)
@since("1.4.0")
[docs] def isSet(self, param):
"""
Checks whether a param is explicitly set by user.
"""
param = self._resolveParam(param)
return param in self._paramMap
@since("1.4.0")
[docs] def hasDefault(self, param):
"""
Checks whether a param has a default value.
"""
param = self._resolveParam(param)
return param in self._defaultParamMap
@since("1.4.0")
[docs] def isDefined(self, param):
"""
Checks whether a param is explicitly set by user or has
a default value.
"""
return self.isSet(param) or self.hasDefault(param)
@since("1.4.0")
[docs] def hasParam(self, paramName):
"""
Tests whether this instance contains a param with a given
(string) name.
"""
if isinstance(paramName, str):
p = getattr(self, paramName, None)
return isinstance(p, Param)
else:
raise TypeError("hasParam(): paramName must be a string")
@since("1.4.0")
[docs] def getOrDefault(self, param):
"""
Gets the value of a param in the user-supplied param map or its
default value. Raises an error if neither is set.
"""
param = self._resolveParam(param)
if param in self._paramMap:
return self._paramMap[param]
else:
return self._defaultParamMap[param]
@since("1.4.0")
[docs] def extractParamMap(self, extra=None):
"""
Extracts the embedded default param values and user-supplied
values, and then merges them with extra values from input into
a flat param map, where the latter value is used if there exist
conflicts, i.e., with ordering: default param values <
user-supplied values < extra.
:param extra: extra param values
:return: merged param map
"""
if extra is None:
extra = dict()
paramMap = self._defaultParamMap.copy()
paramMap.update(self._paramMap)
paramMap.update(extra)
return paramMap
@since("1.4.0")
[docs] def copy(self, extra=None):
"""
Creates a copy of this instance with the same uid and some
extra params. The default implementation creates a
shallow copy using :py:func:`copy.copy`, and then copies the
embedded and extra parameters over and returns the copy.
Subclasses should override this method if the default approach
is not sufficient.
:param extra: Extra parameters to copy to the new instance
:return: Copy of this instance
"""
if extra is None:
extra = dict()
that = copy.copy(self)
that._paramMap = self.extractParamMap(extra)
return that
def _shouldOwn(self, param):
"""
Validates that the input param belongs to this Params instance.
"""
if not (self.uid == param.parent and self.hasParam(param.name)):
raise ValueError("Param %r does not belong to %r." % (param, self))
def _resolveParam(self, param):
"""
Resolves a param and validates the ownership.
:param param: param name or the param instance, which must
belong to this Params instance
:return: resolved param instance
"""
if isinstance(param, Param):
self._shouldOwn(param)
return param
elif isinstance(param, str):
return self.getParam(param)
else:
raise ValueError("Cannot resolve %r as a param." % param)
@staticmethod
def _dummy():
"""
Returns a dummy Params instance used as a placeholder to
generate docs.
"""
dummy = Params()
dummy.uid = "undefined"
return dummy
def _set(self, **kwargs):
"""
Sets user-supplied params.
"""
for param, value in kwargs.items():
self._paramMap[getattr(self, param)] = value
return self
def _setDefault(self, **kwargs):
"""
Sets default params.
"""
for param, value in kwargs.items():
self._defaultParamMap[getattr(self, param)] = value
return self
def _copyValues(self, to, extra=None):
"""
Copies param values from this instance to another instance for
params shared by them.
:param to: the target instance
:param extra: extra params to be copied
:return: the target instance with param values copied
"""
if extra is None:
extra = dict()
paramMap = self.extractParamMap(extra)
for p in self.params:
if p in paramMap and to.hasParam(p.name):
to._set(**{p.name: paramMap[p]})
return to
