Source code for GPy.mappings.constant

# Copyright (c) 2015, James Hensman, Alan Saul
import numpy as np
from ..core.mapping import Mapping
from ..core.parameterization import Param

[docs]class Constant(Mapping): """ A Linear mapping. .. math:: F(\mathbf{x}) = c :param input_dim: dimension of input. :type input_dim: int :param output_dim: dimension of output. :type output_dim: int :param: value the value of this constant mapping """ def __init__(self, input_dim, output_dim, value=0., name='constmap'): super(Constant, self).__init__(input_dim=input_dim, output_dim=output_dim, name=name) value = np.atleast_1d(value) if not len(value.shape) ==1: raise ValueError("bad constant values: pass a float or flat vectoor") elif value.size==1: value = np.ones(self.output_dim)*value self.C = Param('C', value) self.link_parameter(self.C)
[docs] def f(self, X): return np.tile(self.C.values[None,:], (X.shape[0], 1))
[docs] def update_gradients(self, dL_dF, X): self.C.gradient = dL_dF.sum(0)
[docs] def gradients_X(self, dL_dF, X): return np.zeros_like(X)
[docs] def to_dict(self): """ Convert the object into a json serializable dictionary. Note: It uses the private method _save_to_input_dict of the parent. :return dict: json serializable dictionary containing the needed information to instantiate the object """ input_dict = super(Constant, self)._save_to_input_dict() input_dict["class"] = "GPy.mappings.Constant" input_dict["value"] = self.C.values[0] return input_dict