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annotate tvii/sigmoid.py @ 52:0b3daccfc36c

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[documentation] link to lore python lib
author Jeff Hammel <k0scist@gmail.com>
date Sat, 23 Sep 2017 11:18:15 -0700
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1 """
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2 sigmoid function: 1/(1 + e^-z)
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3 """
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5 import numpy as np
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6 from .iterable import isiterable
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8 def sigmoid(z):
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9 """https://en.wikipedia.org/wiki/Sigmoid_function"""
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10 if not isinstance(z, np.ndarray) and isiterable(z):
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11 z = np.array(z)
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12 return 1./(1. + np.exp(-z))
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15 def sigmoidprime(z):
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16 """"derivative of sigmoid"""
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17 return sigmoid(z)*(1-sigmoid(z))