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40 lines
1.1 KiB
Python
40 lines
1.1 KiB
Python
# Copyright (c) 2015, James Hensman, Alan Saul
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import numpy as np
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from ..core.mapping import Mapping
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from ..core.parameterization import Param
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class Constant(Mapping):
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"""
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A Linear mapping.
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.. math::
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F(\mathbf{x}) = c
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:param input_dim: dimension of input.
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:type input_dim: int
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:param output_dim: dimension of output.
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:type output_dim: int
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:param: value the value of this constant mapping
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"""
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def __init__(self, input_dim, output_dim, value=0., name='constmap'):
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Mapping.__init__(self, input_dim=input_dim, output_dim=output_dim, name=name)
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value = np.atleast_1d(value)
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if not len(value.shape) ==1:
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raise ValueError("bad constant values: pass a float or flat vectoor")
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elif value.size==1:
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value = np.ones(self.output_dim)*value
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self.C = Param('C', value)
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self.link_parameter(self.C)
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def f(self, X):
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return np.tile(self.C.values[None,:], (X.shape[0], 1))
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def update_gradients(self, dL_dF, X):
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self.C.gradient = dL_dF.sum(0)
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def gradients_X(self, dL_dF, X):
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return np.zeros_like(X)
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