wehub-resource-sync
40 lines
1.1 KiB
Python
Executable File
40 lines
1.1 KiB
Python
Executable File
import numpy as np
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from prml.nn.tensor.tensor import Tensor
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from prml.nn.function import Function
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class Dropout(Function):
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def __init__(self, prob):
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"""
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construct dropout function
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Parameters
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----------
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prob : float
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probability of dropping the input value
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"""
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if not isinstance(prob, float):
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raise TypeError(f"prob must be float value, not {type(prob)}")
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if prob < 0 or prob > 1:
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raise ValueError(f"{prob} is out of the range [0, 1]")
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self.prob = prob
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self.coef = 1 / (1 - prob)
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def _forward(self, x, istraining=False):
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x = self._convert2tensor(x)
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if istraining:
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self.x = x
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self.mask = (np.random.rand(*x.shape) > self.prob) * self.coef
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return Tensor(x.value * self.mask, function=self)
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else:
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return x
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def _backward(self, delta):
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dx = delta * self.mask
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self.x.backward(dx)
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def dropout(x, prob, istraining):
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return Dropout(prob).forward(x, istraining)
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