# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""Model parameter classes."""
import collections.abc
import copy
import itertools
import numpy as np
from astropy import units as u
from gammapy.utils.table import table_from_row_data
__all__ = ["Parameter", "Parameters"]
def _get_parameters_str(parameters):
str_ = ""
for par in parameters:
if par.name == "amplitude":
line = "\t{:12} {:11}: {:10.2e} {} {:<12s}\n"
else:
line = "\t{:12} {:11}: {:7.3f} {} {:<12s}\n"
frozen = "(frozen)" if par.frozen else ""
try:
error = "+/- {:7.2f}".format(parameters.get_error(par))
except AttributeError:
error = ""
str_ += line.format(par.name, frozen, par.value, error, par.unit)
return str_.expandtabs(tabsize=2)
[docs]class Parameter:
"""A model parameter.
Note that the parameter value has been split into
a factor and scale like this::
value = factor x scale
Users should interact with the ``value``, ``quantity``
or ``min`` and ``max`` properties and consider the fact
that there is a ``factor``` and ``scale`` an implementation detail.
That was introduced for numerical stability in parameter and error
estimation methods, only in the Gammapy optimiser interface do we
interact with the ``factor``, ``factor_min`` and ``factor_max`` properties,
i.e. the optimiser "sees" the well-scaled problem.
Parameters
----------
name : str
Name
value : float or `~astropy.units.Quantity`
Value
scale : float, optional
Scale (sometimes used in fitting)
unit : `~astropy.units.Unit` or str, optional
Unit
min : float, optional
Minimum (sometimes used in fitting)
max : float, optional
Maximum (sometimes used in fitting)
frozen : bool, optional
Frozen? (used in fitting)
"""
def __init__(
self,
name,
value,
unit="",
scale=1,
min=np.nan,
max=np.nan,
frozen=False,
error=0,
):
self.name = name
self._link_label_io = None
self.scale = scale
# TODO: move this to a setter method that can be called from `__set__` also!
# Having it here is bad: behaviour not clear if Quantity and `unit` is passed.
if isinstance(value, u.Quantity) or isinstance(value, str):
val = u.Quantity(value)
self.value = val.value
self.unit = val.unit
else:
self.factor = value
self.unit = unit
self.min = min
self.max = max
self.frozen = frozen
self._error = error
def __get__(self, instance, owner):
if instance is None:
return self
return instance.__dict__[self.name]
def __set__(self, instance, value):
if isinstance(value, Parameter):
instance.__dict__[self.name] = value
# TODO: create the link in the parameters list
# par = instance.__dict__[self.name]
# instance.__dict__["_parameters"].link(par, value)
else:
par = instance.__dict__[self.name]
raise TypeError(f"Cannot assign {value!r} to parameter {par!r}")
@property
def error(self):
return self._error
@error.setter
def error(self, value):
self._error = float(u.Quantity(value, unit=self.unit).value)
@property
def name(self):
"""Name (str)."""
return self._name
@name.setter
def name(self, val):
if not isinstance(val, str):
raise TypeError(f"Invalid type: {val}, {type(val)}")
self._name = val
@property
def factor(self):
"""Factor (float)."""
return self._factor
@factor.setter
def factor(self, val):
self._factor = float(val)
@property
def scale(self):
"""Scale (float)."""
return self._scale
@scale.setter
def scale(self, val):
self._scale = float(val)
@property
def unit(self):
"""Unit (`~astropy.units.Unit`)."""
return self._unit
@unit.setter
def unit(self, val):
self._unit = u.Unit(val)
@property
def min(self):
"""Minimum (float)."""
return self._min
@min.setter
def min(self, val):
self._min = float(val)
@property
def factor_min(self):
"""Factor min (float).
This ``factor_min = min / scale`` is for the optimizer interface.
"""
return self.min / self.scale
@property
def max(self):
"""Maximum (float)."""
return self._max
@max.setter
def max(self, val):
self._max = float(val)
@property
def factor_max(self):
"""Factor max (float).
This ``factor_max = max / scale`` is for the optimizer interface.
"""
return self.max / self.scale
@property
def frozen(self):
"""Frozen? (used in fitting) (bool)."""
return self._frozen
@frozen.setter
def frozen(self, val):
if not isinstance(val, bool):
raise TypeError(f"Invalid type: {val}, {type(val)}")
self._frozen = val
@property
def value(self):
"""Value = factor x scale (float)."""
return self._factor * self._scale
@value.setter
def value(self, val):
self._factor = float(val) / self._scale
@property
def quantity(self):
"""Value times unit (`~astropy.units.Quantity`)."""
return self.value * self.unit
@quantity.setter
def quantity(self, val):
val = u.Quantity(val, unit=self.unit)
self.value = val.value
self.unit = val.unit
def __repr__(self):
return (
f"{self.__class__.__name__}(name={self.name!r}, value={self.value!r}, "
f"factor={self.factor!r}, scale={self.scale!r}, unit={self.unit!r}, "
f"min={self.min!r}, max={self.max!r}, frozen={self.frozen!r}, id={hex(id(self))})"
)
[docs] def copy(self):
"""A deep copy"""
return copy.deepcopy(self)
[docs] def to_dict(self):
"""Convert to dict."""
output = {
"name": self.name,
"value": self.value,
"unit": self.unit.to_string("fits"),
"min": self.min,
"max": self.max,
"frozen": self.frozen,
"error": self.error,
}
if self._link_label_io is not None:
output["link"] = self._link_label_io
return output
[docs] def autoscale(self, method="scale10"):
"""Autoscale the parameters.
Set ``factor`` and ``scale`` according to ``method``
Available methods:
* ``scale10`` sets ``scale`` to power of 10,
so that abs(factor) is in the range 1 to 10
* ``factor1`` sets ``factor, scale = 1, value``
In both cases the sign of value is stored in ``factor``,
i.e. the ``scale`` is always positive.
Parameters
----------
method : {'factor1', 'scale10'}
Method to apply
"""
if method == "scale10":
value = self.value
if value != 0:
exponent = np.floor(np.log10(np.abs(value)))
scale = np.power(10.0, exponent)
self.factor = value / scale
self.scale = scale
elif method == "factor1":
self.factor, self.scale = 1, self.value
else:
raise ValueError(f"Invalid method: {method}")
[docs]class Parameters(collections.abc.Sequence):
"""Parameters container.
- List of `Parameter` objects.
- Covariance matrix.
Parameters
----------
parameters : list of `Parameter`
List of parameters
"""
def __init__(self, parameters=None):
if parameters is None:
parameters = []
else:
parameters = list(parameters)
self._parameters = parameters
@property
def values(self):
"""Parameter values (`numpy.ndarray`)."""
return np.array([_.value for _ in self._parameters], dtype=np.float64)
[docs] @classmethod
def from_stack(cls, parameters_list):
"""Create `Parameters` by stacking a list of other `Parameters` objects.
Parameters
----------
parameters_list : list of `Parameters`
List of `Parameters` objects
"""
pars = itertools.chain(*parameters_list)
parameters = cls(pars)
return parameters
[docs] def copy(self):
"""A deep copy"""
return copy.deepcopy(self)
@property
def free_parameters(self):
"""List of free parameters"""
return self.__class__([par for par in self._parameters if not par.frozen])
@property
def unique_parameters(self):
"""Unique parameters (`Parameters`)."""
return self.__class__(dict.fromkeys(self._parameters))
@property
def names(self):
"""List of parameter names"""
return [par.name for par in self._parameters]
[docs] def index(self, val):
"""Get position index for a given parameter.
The input can be a parameter object, parameter name (str)
or if a parameter index (int) is passed in, it is simply returned.
"""
if isinstance(val, int):
return val
elif isinstance(val, Parameter):
return self._parameters.index(val)
elif isinstance(val, str):
for idx, par in enumerate(self._parameters):
if val == par.name:
return idx
raise IndexError(f"No parameter: {val!r}")
else:
raise TypeError(f"Invalid type: {type(val)!r}")
def __getitem__(self, name):
"""Access parameter by name or index"""
idx = self.index(name)
return self._parameters[idx]
def __len__(self):
return len(self._parameters)
def __add__(self, other):
if isinstance(other, Parameters):
return Parameters.from_stack([self, other])
else:
raise TypeError(f"Invalid type: {other!r}")
[docs] def to_dict(self):
data = []
for par in self._parameters:
data.append(par.to_dict())
return data
[docs] def to_table(self):
"""Convert parameter attributes to `~astropy.table.Table`."""
rows = [p.to_dict() for p in self._parameters]
table = table_from_row_data(rows)
for name in ["value", "error", "min", "max"]:
table[name].format = ".3e"
return table
def __eq__(self, other):
all_equal = np.all([p is p_new for p, p_new in zip(self, other)])
return all_equal and len(self) == len(other)
[docs] @classmethod
def from_dict(cls, data):
parameters = []
for par in data:
link_label = par.pop("link", None)
parameter = Parameter(**par)
parameter._link_label_io = link_label
parameters.append(parameter)
return cls(parameters=parameters)
[docs] def set_parameter_factors(self, factors):
"""Set factor of all parameters.
Used in the optimizer interface.
"""
idx = 0
for parameter in self._parameters:
if not parameter.frozen:
parameter.factor = factors[idx]
idx += 1
[docs] def autoscale(self, method="scale10"):
"""Autoscale all parameters.
See :func:`~gammapy.modeling.Parameter.autoscale`
Parameters
----------
method : {'factor1', 'scale10'}
Method to apply
"""
for par in self._parameters:
par.autoscale(method)
@property
def restore_values(self):
"""Context manager to restore values.
A copy of the values is made on enter,
and those values are restored on exit.
Examples
--------
::
from gammapy.modeling.models import PowerLawSpectralModel
pwl = PowerLawSpectralModel(index=2)
with pwl.parameters.restore_values:
pwl.parameters["index"].value = 3
print(pwl.parameters["index"].value)
"""
return restore_parameters_values(self)
[docs] def freeze_all(self):
"""Freeze all parameters"""
for par in self._parameters:
par.frozen = True
class restore_parameters_values:
def __init__(self, parameters):
self._parameters = parameters
self.values = [_.value for _ in parameters]
self.frozen = [_.frozen for _ in parameters]
def __enter__(self):
pass
def __exit__(self, type, value, traceback):
for value, par, frozen in zip(self.values, self._parameters, self.frozen):
par.value = value
par.frozen = frozen