theano.gof.params_type
– Wrapper class for op params¶
Reference¶
Module for wrapping many Op parameters into one object available in both Python and C code.
The module provides the main public class ParamsType
that allows to bundle many Theano types
into one parameter type, and an internal convenient class Params
which will be automatically
used to create a Params object that is compatible with the ParamsType defined.
The Params object will be available in both Python code (as a standard Python object) and C code (as a specific struct with parameters as struct fields). To be fully-available in C code, Theano types wrapped into a ParamsType must provide a C interface (e.g. TensorType, Scalar, GpuArrayType, or your own type. See Using Op params for more details).
Example of usage¶
Importation:
# Import ParamsType class.
from theano.gof import ParamsType
# If you want to use a tensor and a scalar as parameters,
# you should import required Theano types.
from theano.tensor import TensorType
from theano.scalar import Scalar
In your Op sub-class:
params_type = ParamsType(attr1=TensorType('int32', (False, False)), attr2=Scalar('float64'))
If your op contains attributes attr1
and attr2
, the default op.get_params()
implementation will automatically try to look for it and generate an appropriate Params object.
Attributes must be compatible with the corresponding types defined into the ParamsType
(we will try to convert and downcast if needed). In this example, your_op.attr1
should be a matrix of integers, and your_op.attr2
should be a real number (integer or floating value).
def __init__(value_attr1, value_attr2):
self.attr1 = value_attr1
self.attr2 = value_attr2
In perform()
implementation (with params named param
):
matrix_param = param.attr1
number_param = param.attr2
In c_code()
implementation (with param = sub['params']
):
PyArrayObject* matrix = param->attr1;
npy_float64 number = param->attr2;
/* You won't need to free them or whatever else. */
See QuadraticOpFunc
and QuadraticCOpFunc
in theano/gof/tests/test_params_type.py
for complete working examples.
Combining ParamsType with Theano enumeration types¶
Theano provide some enumeration types that allow to create constant primitive values (integer and floating values)
available in both Python and C code. See theano.gof.type.EnumType
and its subclasses for more details.
If your ParamsType contains Theano enumeration types, then constants defined inside these enumerations will be directly available as ParamsType attributes.
Example:
from theano.gof import ParamsType, EnumType, EnumList
wrapper = ParamsType(enum1=EnumList('CONSTANT_1', 'CONSTANT_2', 'CONSTANT_3'),
enum2=EnumType(PI=3.14, EPSILON=0.001))
# Each enum constant is available as a wrapper attribute:
print(wrapper.CONSTANT_1, wrapper.CONSTANT_2, wrapper.CONSTANT_3,
wrapper.PI, wrapper.EPSILON)
# For convenience, you can also look for a constant by name with
# ``ParamsType.get_enum()`` method.
pi = wrapper.get_enum('PI')
epsilon = wrapper.get_enum('EPSILON')
constant_2 = wrapper.get_enum('CONSTANT_2')
print(pi, epsilon, constant_2)
This implies that a ParamsType cannot contain different enum types with common enum names:
# Following line will raise an error,
# as there is a "CONSTANT_1" defined both in enum1 and enum2.
wrapper = ParamsType(enum1=EnumList('CONSTANT_1', 'CONSTANT_2'),
enum2=EnumType(CONSTANT_1=0, CONSTANT_3=5))
If your enum types contain constant aliases, you can retrive them from ParamsType
with ParamsType.enum_from_alias(alias)
method (see theano.gof.type.EnumType
for more info about enumeration aliases).
wrapper = ParamsType(enum1=EnumList('A', ('B', 'beta'), 'C'),
enum2=EnumList(('D', 'delta'), 'E', 'F'))
b1 = wrapper.B
b2 = wrapper.get_enum('B')
b3 = wrapper.enum_from_alias('beta')
assert b1 == b2 == b3
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class
theano.gof.params_type.
Params
(params_type, **kwargs)[source]¶ Internal convenient class to wrap many Python objects into one (this class is not safe as the hash method does not check if values are effectively hashable).
Example:
from theano.gof import ParamsType, Params from theano.scalar import Scalar # You must create a ParamsType first: params_type = ParamsType(attr1=Scalar('int32'), key2=Scalar('float32'), field3=Scalar('int64')) # Then you can create a Params object with # the params type defined above and values for attributes. params = Params(params_type, attr1=1, key2=2.0, field3=3) print(params.attr1, params.key2, params.field3) d = dict(attr1=1, key2=2.5, field3=-1) params2 = Params(params_type, **d) print(params2.attr1, params2.key2, params2.field3)
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class
theano.gof.params_type.
ParamsType
(**kwargs)[source]¶ This class can create a struct of Theano types (like TensorType, GpuArrayType, etc.) to be used as a convenience op parameter wrapping many data.
ParamsType constructor takes key-value args. Key will be the name of the attribute in the struct. Value is the Theano type of this attribute, ie. an instance of (a subclass of)
Type
(eg.TensorType('int64', (False,))
).In a Python code any attribute named
key
will be available via:structObject.key
In a C code, any attribute named
key
will be available via:structObject->key;
Note
This Type is not complete and should never be used for regular graph operations.
-
has_type
(theano_type)[source]¶ Return True if current ParamsType contains the specified Theano type.
-
get_type
(field_name)[source]¶ Return the Theano type associated to the given field name in the current ParamsType.
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get_field
(theano_type)[source]¶ Return the name (string) of the first field associated to the given Theano type. Fields are sorted in lexicographic order. Raise an exception if this Theano type is not in the current ParamsType.
This method is intended to be used to retrieve a field name when we know that current ParamsType contains the given Theano type only once.
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get_enum
(key)[source]¶ Look for a constant named
key
in the Theano enumeration types wrapped into current ParamsType. Return value of the constant found, or raise an exception if either the constant is not found or current wrapper does not contain any Theano enumeration type.Example:
from theano.gof import ParamsType, EnumType, EnumList from theano.scalar import Scalar wrapper = ParamsType(scalar=Scalar('int32'), letters=EnumType(A=1, B=2, C=3), digits=EnumList('ZERO', 'ONE', 'TWO')) print(wrapper.get_enum('C')) # 3 print(wrapper.get_enum('TWO')) # 2 # You can also directly do: print(wrapper.C) print(wrapper.TWO)
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enum_from_alias
(alias)[source]¶ Look for a constant that has alias
alias
in the Theano enumeration types wrapped into current ParamsType. Return value of the constant found, or raise an exception if either- there is no constant with this alias,
- there is no constant which name is this alias, or
- current wrapper does not contain any Theano enumeration type.
Example:
from theano.gof import ParamsType, EnumType, EnumList from theano.scalar import Scalar wrapper = ParamsType(scalar=Scalar('int32'), letters=EnumType(A=(1, 'alpha'), B=(2, 'beta'), C=3), digits=EnumList(('ZERO', 'nothing'), ('ONE', 'unit'), ('TWO', 'couple'))) print(wrapper.get_enum('C')) # 3 print(wrapper.get_enum('TWO')) # 2 print(wrapper.enum_from_alias('alpha')) # 1 print(wrapper.enum_from_alias('nothing')) # 0 # For the following, alias 'C' is not defined, so the method looks for # a constant named 'C', and finds it. print(wrapper.enum_from_alias('C')) # 3
Note
Unlike with constant names, you can NOT access constants values directly with aliases through ParamsType (ie. you can’t write
wrapper.alpha
). You must usewrapper.enum_from_alias()
method to do that.
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get_params
(*objects, **kwargs)[source]¶ Convenient method to extract fields values from a list of Python objects and key-value args, and wrap them into a
Params
object compatible with current ParamsType.For each field defined in the current ParamsType, a value for this field is looked for in the given objects attributes (looking for attributes with this field name) and key-values args (looking for a key equal to this field name), from left to right (first object, then, …, then last object, then key-value args), replacing a previous field value found with any value found in next step, so that only the last field value found is retained.
Fields values given in objects and kwargs must be compatible with types associated to corresponding fields in current ParamsType.
Example:
import numpy from theano.gof import ParamsType from theano.tensor import dmatrix from theano.scalar import Scalar class MyObject: def __init__(self): self.a = 10 self.b = numpy.asarray([[1, 2, 3], [4, 5, 6]]) params_type = ParamsType(a=Scalar('int32'), b=dmatrix, c=Scalar('bool')) o = MyObject() value_for_c = False # Value for c can't be retrieved from o, so we add a value for that field in kwargs. params = params_type.get_params(o, c=value_for_c) # params.a contains 10 # params.b contains [[1, 2, 3], [4, 5, 6]] # params.c contains value_for_c print(params)
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